If it's crap ... We'll tell you
Some good series in my opinion:
I would watch them in japanese, because they tend to cut off important scenes in the dubbed american versions.
Code Geass (people usually say this is for the more serious crowd)
Gundam 00 (the only one of the series i liked)
some I just enjoyed
Remake of Hellsing
High School of the Dead
And by extension, would not 90% of american animation be anime, by this reasoning?
To be honest, I haven't seen a lot of anime, but out of the stuff I have seen, "Spirited Away" is my favorite.
I'm surprised that only one person has given the Ghost in the Shell TV series any props. That was an amazing show and it really brought a lot more to the characters that couldn't be fleshed out in the movies. The writing is just incredible and the second season really outdid the first.
Last Exile is also one of my favorites. Not only do I love airships, but I thought the idea of Napoleonic stylization mixed with fantasy was pretty fresh and it's something that's definitely not done enough. It also ends in a way that isn't vague or unsatisfying at all.
Everyone else has pretty much listed most of the other anime I've found really amazing.
I used to sneak to watch Aeon Flux when it came on MTV in the early 90s. When I left for college a friend of mine and her husband introduced me to Ranma 1/2 and Fruits Basket
yu yu hakusho