The OPPOSITE of the worst Cartoon/Anime you have ever seen, anyways to stay on topic...
Mine would probably be...
Naruto
Bleach ( Since it will stop airing to make room for Death Note...Death Note better be good >.<)
Full Metal Alchemist (Sad...only lasted 51 episodes)
Bo-BoBo (Hey, it was one of the first Animes I ever watched)
Prince of Tennis (I have no idea why)