(Relative to their universe or normal power set?)
One example is Animal man
thread in cbr
For those to bored to go thorough it, copying the abilities of any animal means he could be 850 times stronger than normal (Rhinosarus beetle), could take a spear shrimps spear (Which shoots with the force of a bullet at 50 m/s, 10,400 g underwater), could take the powers of Bacterium to replicate like crazy, starfish for regeneration, once when taking the durability of a Rhino he shrugged of a 747 crashing into him for Fun.
At the end of his series he could mix and match freely and apparently take the properties of any aniaml/non human that died on earth.
Such as Krypto, white martians, etc...

Potentially he could have the versatility to make MM or Superman look one dimensional, as well as being almost impossible to kill.
Another Example is:
Bookworm
The power to create and control any fictional character is a lot scarier if say, he read the bible or Hyperion books or DC comics (Which do exist in marvel verse).
Yet another is The Flash.
Quite simply if he always functioned at his standard high level (not peak) his reaction times are far beyond the pico-secs, he can turn on the speed instantly, time travel, make punches that can hurt Superman badly, travel in time at will and possibly change it, steal speed from anyone else and add it to his own combined with his ability to break c speeds.
Also the classic is Superman, if he functioned at his normal high levels, used all the equipment at his disposal (Alien warlord weapons, a GL ring, Superman robots nearly identical to him, Kryptonian armour(s), ultra high tech from the fortress etc...) or if he used the Sun dip to reach planet moving strengths regularily or decided to Kill (Action comics 775 has a fantastic story about how dangerous he would be if he took of the kid gloves) or maintained his speeds of near c.
The fact is he could destroy earth easily, or annihalate it's ozone layer also (He threatened to do this to make the 4 eleemtal forces stop attacking him once).