I'd have to say to watch Fairy Tail, Rave Master, Tears to Tiara, dnangel, gravitation, beck, hellsing Ultimate (I kind of dislike most of the original series - mainly last few eps) Slayers, dragon ball z, ranma, fullmetal alchemist, fullmetal alchemist brotherhood (both series follow the same plot to a certain extent though the former one diverges from the plot since it came out years before the manga was even complete. I also prefer how they animated Brotherhood, it's so much superior.) detective conan/case closed.

one series i couldn't stand and probably never will: Reign the conqueror... I absofreakinlutely hated how it was animated, the story, etc... the only reason i watched it was because two series I loved came on before and after it came on. My brother loved it so it's not that bad. other people i know liked it.