Yeah, i'm a big fan, I love it from an artistic point of view, I especially like the layering techniques as well as the stories. In the East animation is treated more as another medium, another artform, wheras in the west we tend to think that cartoons are just for kids.
I know you can say things like South Park and Family Guy and the like are aimed at adults, which they are, but thats kind of the point, they are AIMED AT ADULTS. In the East it would just be aimed at and accepted by everyone.
I like loads of things from widespread appeal to weird little indie animes.
Devilman - absolutely great, blew me away when I was a young lad.
Dragonball, Z, GT - All great in a way of progression with over 500 episodes of epic-ness.
Naruto - Come on we all like ninja
Fist Of The North Star - great brutality, especially when younger and used to the turtles or something, lol
Death Note - Just been getting in to it after meaning to for ages, brilliantly different than the norm.
These are just a few series to name a few, good old Manga films like Patlabor, Akira, Ghost In The Shell, Spirited Away are all pretty enjoyable too.
Oh and I prefer to watch with Japanese subtitles (even if they can be variable), the voices sound better and stuff isn't cut and dumbed down for a younger audience.