Ghost in the Shell: Stand Alone Complex is brilliant.
Cowboy Bebop is still the king of anime after all these years, both the TV series and the movie.
Anything by Satoshi Kon is worth checking out. Serious, serious mindf**ks though. He really messes with your head.
There are also some great comedy animes. Fullmetal Panic? Fumoffu (that's the name) is utterly hilarious. Netflix it. It's so worth it.