If I had the superpower(s) of an existing superhero or villain, it would be...

[jonchang]

DC

Definitely the Martian Manhunter. He is the  "Swiss army knife" of superheroes. Numerous abilities, all very versatile. According to DC Database (apologies for taking up a lot of space):

Shape-Shifting, Malleability, Plasticity, Elongation: The most incredible of the powers of the Manhunter is the ability to shape-shift. He is able to literally control the molecular structure of his body's bio-polymer and make it resemble anything he wants. He can form clothing, weapons with nonmoving or nonfunctioning parts (so he could form a sword from his body's mass and it would work, but a gun would not, unless he was carrying some ammunition with him.) There does not seem to be any limit to the number of people the Manhunter can imitate and has stood in as a double for many famous people. His ability to imitate people and their mannerisms has stood him in good stead for his disguises. It is rumored that he could change his shape in more fantastic ways but has yet to be substantiated. He has recently been seen to shape-shift into the size and shape of a common house fly to enormous sizes comparable to skyscrapers. He is also able to change colors.

Invisibility: The Manhunter can cause the bio-polymers in his body to lose his ability to reflect light, rendering the Manhunter invisible to normal light and human sight. With more increased concentration, he can render himself more invisible along the electromagnetic spectrum, including the infrared and the ultraviolet ranges of the spectrum. Such increase range, however, reduces the amount of time he can maintain his invisibility. This invisibility does not affect other senses and he could still be detected by sound, smell or touch.

Phasing: No physical explanation of this power make sense except that it is an aspect of his psionic powers shifting his mass into another dimension or out of vibrational phase with other objects in this dimension. Whichever it is, it has been seen rarely and believed to be difficult to maintain for extended periods.

Superhuman Durability: The Manhunter's durability is no where near Superman's level, as proven by the battle against Doomsday. Doomsday, defeated the entire Justice League with a single blow for each member. Overall, the bio-morphic structure of the Manhunter's body allows him to absorb most kinetic energies such as bullets, shrapnel or flying debris. Attacks of a nature greater than that, he can harden his bio-polymers by rebinding them and become nearly 10 times as resistant to damage as steel. Hazardous environments effect the Manhunter less than normal humans and he seems to recover from them much more quickly. He has proven to be immune to most human diseases, but no experimentation has been done to see what more advance viruses such as ebola or anthrax might have.

Superhuman Strength: The Martian's superhuman strength comes from his plasmorphic structure formed from immensely long and complex molecular chains, augmented with his psionic and telekinetic abilities allowing him to lift incredible weights without these weights crumbling under the stress. The Martian has been seen lifting small tankers out of the ocean for short distances. By modifying the density of these bio-polymers, the Manhunter can make himself stronger by forcing the polymers into tighter bundles. At a rest state, the Manhunter can lift at least a 100 tons. Given a few minutes to reconfigure,he can lift far in excess of this amount and also he could match Superman pound for pound, but for a limited amount of time. Then the bio-polymer would begin to suffer under the strain and begin to unravel. While the Manhunter's strength can be on par with Superman, he still lacks the long term endurance and stamina of the Kryptonian. This probably has to do with the Kryptonian's storage and creation of Meta ATP which the Martian biology would not have developed being so far from the Earth's sun.

Superhuman Endurance: J'onn's endurance is just as formidable as his strength or invulnerability. When not in the presence of fire, he can operate under extreme conditions for an indeterminate period of time without showing signs of fatigue. The exact range of this power is unknown.

Flight: The Martian Manhunter flies by manipulation of gravitons (a subatomic particle associated with the force of gravity) manipulation of magnetic fields and control of his absolute molecular movement (a telekinetic effect). These combine to give him the ability to fly great distances with little fatigue and at great speed. He has been seen to fly at Mach 10 speeds (7690mph) in the Earth's atmosphere. Speeds faster than this cause great environmental damage and are avoided unless absolutely necessary. His bio-polymorphic skin and overall toughness make these speeds bearable and cause him no lasting injury. The Manhunter has also been seen to fly in space with no difficulty though he must hold his breath or have his own supply of oxygen in order to stay in space for long periods of time. Noting his methods of flight, he should be able to be detected with any technology that can detect graviton emissions..

Superhuman Speed: Either through flight or natural movement, the Martian Manhunter can maintain speed and reflexes far in excess to that of a standard Earth human. Like the power of flight, this is accomplished by manipulating the magnetic fields of energy surrounding his body, as well as ambient gravitational particles. Traditionally, J'onn only uses his superhuman speed while flying. His super-speed, while impressive, is not comparable to that of the Flash. But at least enough to move in excess of escape velocity (7 miles a second) as he countlessly has escaped the Earth's gravity. He can process thoughts, move, and react at superspeed.

Extrasensory Input: J'onn possesses nine different senses. One of these senses could account for instances of the Manhunter's perceived precognitive abilities.

Longevity

Super Hearing

Super Breath: The ability to create hurricane force winds by blowing.

Martian Vision: The actual nature of this power seems to vary depending on the reports. It has been seen to be a bolt of force, directed by the Manhunter's eyes causing considerable damage, equivalent to 50-100 lbs of TNT. It has also been seen to cause flammable objects to catch fire. The range of this power is also unknown but has been seen to be effective at ranges of 500 feet or more. Judging from the infrequency of use, it must have a high energy cost or reduce the Martian's effectiveness in some way. It also grants J'onn the ability to see into other spectrums of light. J'onn can use his Martian vision to see the invisible. For example, upon their first meeting, J'onn's power allowed him to see past Gypsy's Metahuman camouflage ability (although this may also be due to the fact that Gypsy is part Martian); other effects unknown.

Infared Vision

X-Ray Vision

Telescopic Vision

Microscopic Vision

Telepathy: The Manhunter is considered a Class 3 telepath. He is able to read the mind of any normal human with no difficulties, assuming that human is not insane, of normal willpower and has received no special telepathic block training. Given a few seconds to concentrate, he can even read their subconscious mind as well. Has been seen mind scanning every person on Earth within a matter of minutes. Has been seen scanning the minds of people in countries surrounding him in seconds. He can read a normal mind over distances of even a mile, if he knows where the target is located. He can use his telepathy with minds that he is familiar with anyplace in the world, as long as he was attuned to that person in the first place. This telepathy extends to distances as far away as the moon, since it is known that the Martian Manhunter can communicate with Earth with his telepathy. It is not known whether there is a limit to the number of people he can be attuned to or whether there are any special requirements to being attuned to him. In addition to reading minds, the Martian Manhunter can literally reprogram the mind of a subject into believing whatever he wants them to. He can use this ability to help subjects forget things that he does not want them to remember as well as set up post-hypnotic suggestions. How long such mental conditioning lasts is unknown. [6]

Illusions

Induce Sleep

Mind Scans

Mind Wipes

Mental Shield: He can prevent other telepaths from reading his mind. With more effort and concentration, he can expand this ability and shield other people from telepathy.

Download Information: Has demonstrated this by downloading information on how to fly a martian space ship into Batman's brain.

Limited Mind Control: Insanity and minds that are too "different" for telepathy to work seem to be his only limits.

Thought Sensing: The Manhunter can use the mental signature of a being to track it and can detect lifeforms by their empathic as well as telepathic signatures. He can detect whether a being is intelligent and can communicate with it empathically if it does not have a communication driven frame of reference for normal telepathy to function with. He can also detect various states of mind from anywhere in the world of the general populace in that area.

Telepathic Relay: Other wise known as a telepathic link. As a Class 3 telepath, the Manhunter is able to use his telepathic prowess as a relay station for a group of minds, who can then "speak" to each other through him. This relaying ability seems to be limited to the same range as the Manhunter's normal telepathic range.

Telepathic Assault: The Martian Manhunter can also use his telepathic abilities in an offensive manner. He has the ability to cause mental shutdown in a target using his mental powers. This effect has a duration of about an hour and unless the target possesses mental powers of their own, do not seem to be able to resist the attack. The Manhunter does not use this power often due to the invasive nature and harshness of such a telepathic attack. Using this power also drains him considerably and reduces his telepathic effectives for a time.

Marvel

Blackheart. Like, the Manhunter, he has many versatile abilities, and range can rival even those the level of Thanos. According to Marvel Database, his abilities are:

Vast energy manipulation (seemingly unlimited but so far we have seen:

Dark Energy: A blast of pure dark energy that can be transferred from a concussion blast, to a dark fire, to dark lightning.

Ice Energy: He can blast a beam (or several) of super cold energy and freeze anything in it's way.

Elemental manipulation: He can manipulate the four elements of Earth (fire, water, earth, air) to unknown levels. He has been known to turn water into ice and rock into magma.

Light Manipulation: He can manipulate light to unknown levels. He has made "Prysm blasts" from the light energy of the sun.

Magical Energy Manipulation: He can manipulate magical energys to do nearly anything he wants.

Psychic energy: he can use his psycic power to create energy blasts and shields.

Shadow Manipulation: He can manipulate the shadows around him by magically controlling them.

Invulnerability (he is essensially nigh-invulnerable to anything but the most powerful magic and cosmic power (Phoenix Force, etc)

Telekinesis (He can mentally manipulate and control any form of matter down to the subatomic level. He can rearrange the molocules of objects in order to change their form. On one ocassion he ripped apart an entire planet through a sheer force of will. His telekinetic powers seem to be unlimited in power)

Telepathy (he is able to read the minds of others and project his own thoughts into other's minds. He has several other abilities that include:

Telepathic Illusion: ability to create realistic telepathic illusions and cause people to experience events which are not actually occurring

Telepathic Cloak: Can mask his presence from being detected by others. His abilities can at times go undetected or be counteracted by other more powerful telepaths depending on their level of skill in using their own psi abilities. He can extend these defenses to others around him as well.

Mind Blast: ability to place large amounts of information in another's mind.
Mind Control: ability to control the minds of others upon mere concentration. This power can allow him to completely shut down several peoples' minds, making it appear as if time has stopped.

Mind Possession: ability to possess the mind of another, and use that being's body as his own.

Mind Alteration: ability to alter the minds of others by force of will.

Mental Amnesia: ability to cause loss of particular memories, and amnesia in another person or even in a group of people

Psionic Shield: ability to erect a psychic shield for protection of himself and of others minds

Psionic Blasts: can project psionic force bolts which have no physical effects but which can affect a victim's mind so as to cause the victim pain or unconsciousness and can even kill an adversary.

Superhuman Speed (Blackheart can think, move, and react at a rate near the speed of light)

Levitation (magical flight) (Blackheart can use his magic to fly and combine his superspeed with his flight essenssially allowing him to fly at speeds that are near the speed of light)

Superhuman Strength (He can lift an excess of 100 tons, but no limit has actually been set)

Super Enhanced Senses (Blackheart has a amazing superhuman sense of sight, hearing, touch, and smell. He has no mouth, so he has no reason for a sense of taste)

Regeneration (Blackheart has the ability to regenerate from virtually any form of damage. From a simple scratch to a missing limb, he can even reform himself after total particle vaporization by combining all of his remaining energy together and creating a cell, which he will then regenerate from.)

Energy Suppression (he can supress other being's powers and energy making then unusable to his opponent, seemingly unlimited)

Reality Manipulation (his reality warping powers are comparable to Franklin Richards when his power isn't suppressed)

Control over the Darkforce Dimension (Blackheart can manipulate and use the power of the Darkforce Dimension to unlimited lengths. He is able to teleport himself and others into the dimension and when in the dimension he is literally omnipotent, omniscient and omnipresent. Many believe that Blackheart makes the Darkforce Dimension his home dimension. )

High level of mental demonic manipulation and control over other beings (seemingly unlimited):  can command legions of demons and monsters

Intangibility (He can make himself intangible at will, thus giving him phasing)

Teleportation (He can teleport himself and others through space and time itself; no limit to this power has been seen)

Astral Projection (can create intangible copies of himself)

Invisibility (he can make himself and others around him invisible by mentally bending the wavelengths of light around himself without creating any distortion effects. He can also use magic to do this in order to avoid any confrontation with those who can see through his normal invisibility, again such as the Invisible Woman.)

Physical Copies (He can use his magic to make solid the intangible copies of himself, but they have no free will of their own and are at his total control)

Shapeshifting (He can take any form he chooses. This power also includes extending body parts or growing larger or smaller at will and changing the phyiscal form of any part of him)

Hyper Psionic energy (draws nearly infinite psionic energy from hyperspace and can control the four fundamental forces of the universe)

High levels of Matter Manipulation (seemingly unlimited and he can manipulate matter to the subatomic level)

Interdimensional Transportation (Can transport himself and others to any plane of existence he wishes, and can enter and leave any number of dimensions he wishes.)

Post which Marvel and which DC character's superpowers you wish you could have.

[bleedingcowz]

DC

Amazo rocks, especially cause he's an android

Absorption Cells: Although he does not really have super powers because he is an android, his "absorption cells" are pretty cool, and can mimic all
kinds of powers and technology like weapons and etc. P

Marvel

Taskmaster, even after he got his ass handed to him by deadpool, still r0xx0rz!

Photographic Reflexes: Similar to photographic memory, anything Taskmaster sees he can copy, thus he is dependent on his sight. And although he can reproduce even the most complicated moves, he cannot perform moves that Meta-humans or Powered beings can do can do (Such as those with super strength or any other special abilities).

As you can see i like to keep it pretty simple.

[Rasdel]

Ok... my turn...

DC... normally i like Superheroes, but in this case i'll make an exception since i am a HUGE fan of "spontaneous regenerative characters" (aka Wolvie, Deadpool, Hulk, etc)

---LOBO---
Superhuman strength, stamina, and durability,
Superhuman sense of smell,
Regenerative healing factor^^(i just love this!)
Immortality^^(Yippie!)
Genius level intellect^^(Reed who?)
Able to track anyone or anything across galaxies.^^ (you can run, but you can't hide)

I would pretty much own! XD

---MARVEL---
I would say Sentry... but he got his @$$ wooped by one of my trully favorites... The Jolly Green Giant...

A.K.A

The HULK


Hulk is definitly my favorite power-wise, specially now that he is not... erm... how can i put this... "dumb" ^^

Cheers

[Noelemahc]

DC

The Hit-Man, naturally. If a specific brand of sarcasm can be written down as a superpower. Oh, and he can also read people's thoughts. And sometimes see through walls. And he's dead for a looong while now

Marvel

This is hard I wanna say "Taskmaster", but the way I learn most physical actions is not much dissimilar from what he does, so that would border on redundancy (N.B. in his solo series he DID copy superpowered moves, i.e. ones depending on superspeed or superstrength; it's just very damaging to his body for obvious reasons). Instead, I'd opt for someone like... I don't know, really, the Marvel approach to superheroes always balances a power with some negatives, and that won't do. So let's pick Crimson Dynamo's armour and leave it at that

[thunderstruck113]

dc

martian manhunter and zatanna

psionic powers
super strenght
density manipulation
magic

marvel
phoenix,storm,magneto

magnetokinesis
telekinesis
atmokinesis
telepathy
omega level cosmic pyrokinesis!

[muafan]

dc.
GL.


marvel.