I'm kind of dissapointed Edward Elric wasn't included in this list, he went through so much in Full Metal Alchemist that he became much more acceptable as a normal human who practically defeated the Father of homunculus using just alchemy and his bare fists.
I'd have to go with Goku since he's in a league of his own. But if I had to choose someone other than him I'd go with Hao from Shaman King (manga version) since he's just unbeatable.
Goku in term of physical power but... in overall power it will be Shiki Ryougi in third personality >_< coz she can cut everything including the reality itself ^_^
Simon from TTGL.
I mean, how can you compete with a guy in a mecha the size of a galaxy that exists outside of time and space yet can still hit you and has no power limit?
You can't.