I have to stick with Samus over everyone else. No other character gets close to her badassedness, especially in the newer games.
I hate a lot of characters but Waluigi has ALWAYS annoyed the hell out of me. Wario is right up there. Any pokemon past 152 for me, I loved Mew. Diddy Kong annoys me, which is weird since I never played any games that had him (thought it was a girl until the Dojo called her a he).