Neon Genesis Evangelion.
Jesus fucking christ that was the best series I've ever seen. Amazing character and interaction combined with giant robots that fucking BLEED, deep examinations of the nature of humanity.
And you could watch it in different ways - you could simply view it as a robot action show or you could actually look into all the intricacies put in.
Edit: Gurenn Lagan (even though I've only seen the second movie, GODDAMN) is pretty cool.
Detroit Metal City was probably the funniest thing I've seen in a long while.