Trinity Blood and Blood + are both completely retarded.

Bleach is decent, though the fanbase is annoying. Not as bad as the Naruto fanbase, but still pretty awful.

Death Note started good but then just got pointless when they started skipping important parts of plot from the manga.

FLCL is naturally amazing.

I've stated it before, but the Melancholy of Haruhi Suzumiya, while an obvious choice, is easily the best I've seen.