If you can name one cartoon that pulls off amazing visuals or great leaps and stunning martial arts i would like to see it.
Just about any disney movie looks great, and what little fighting they do have looks very good. (aladdin, the lion king, etc.)
For older stuff, heavy metal and wizards were incredibly awesome looking for their time, and had battle.
Heavy metal 2000 continues this trend of the first.
(note that heavy metal and heavy metal 2000 were made in canada, but i'm lumping it in with american animation, since the US and canada have about the same ecosystem when it comes to TV and movies.)
Hercules and Xena - The Animated Movie: The Battle for Mount Olympus looked great and had a ton of fighting.
the Gargoyles TV series (and i suppose accompanying direct-to-video movie, though i've never seen it) was very well animated, and had a pretty decent storyline to go with it.
Batman: The animated series. 'Nuff said there.
Xmen the animated series.
Also: not every anime has top-notch visuals either. The old speed racer, astroboy (but i wont lie about my love of either of these two series. Also, ive always seen their bad animation as part of their charm.), shinchan (though i think that one has bad visuals intentionally)
I could probably go on, but these are just off the top of my head.
Point is: American, asian, european and whatever nationality/region/whatever you want to pick has produced good and bad content.
Also: Quality of visuals is largely opinion.
ryos, have you seen Cowboy Bebop? It's Brandon's favorite anime, and he says he's never seen a U.S. series as well done.
I LURRRRRRRRRVS me some cowboy bebop.