Having only actually read Alan Moore graphic novels, my vote goes to the mighty Walter Kovacs. I can definitely relate to the Batman fans though, but my only experience is the films. I seem to generally prefer non-supers, as well as DC creations.

*contemplates getting his paws on some Batman comics* Does anyone have any reccomendations?

...but "The Dark Knight Returns" limited series has always been one of my favorite Batman romps.

"The Killing Joke" was great, too.

No one has mentioned the Merc with the Mouth, Deadpool?! What is not to love about a clinically insane smart mouth who uses katanas, guns, bombs, or whatever else, can teleport, AND has a (unreliable) healing factor?

Deadpool is by far my favorite Marvel "hero" but I think I'd have to go with Beast Boy for DC, gotta love a shapeshifter. And lets not forget the non-Marvel/DC "heroes" Spawn is an amazing character as well, and I'm very surprised no one has mentioned him either

As for Villians, Marvel I think I'd have to say Carnage, but DC hands down it would be the Joker, he may not be a so-called "super villain" but with no powers he has managed to do so much more than some supers..