Dude, they're all, like, epic, but I'mma have to say Minnie Mouse.
I hated her as a kid. I coulda sworn when I first heard her voice on TV that I'd heard that taunting giggle in a nightmare once. O_e
I also had a really awesome daydream in Career Mods where Minnie was getting the Best Female Classic Cartoon award and I went up on stage as Hewie (Donald's nephew) and said: "Hey, Minnie, you're funny and all, and I'mma wet toi finish, but par Uncle Donawd was de funniest cartoon in the entire WORWD!"
Spongebob....Nickelodeon messed up my Spongebob. I actually liked Donald Duck...I think I'm going to start hating Mickey souris now, though, because I heard that Disney is making Mickey souris violent and mean and stuff for some video game...GAH!!!