I find it funny that, for the most part, the anime and manga that Americans like are those they see off of TV - there's a hell of a lot more anime than that displayed on Cartoon Network, you know. ;D
Personally, I've got to say FLCL, Cowboy Bebop, Ghost in the Shell 1 and 2 (the movies, not the horrendous anime series depictions), Serial Experiments Lain, and Fist of the North Star are my favorite anime productions. Miyazaki makes some pretty good stuff too, though - I'll happily watch anything he's produced.