Voltron and Astroboy in the mid 80s. In fact even animators loved Japanese style so much that most of cartoons I grew up with were actually animated in Japan, or at least with Japanese animators.
I actually know a few cartoons right now off the top of head that were animated in Japan but are strictly American all because the company loved the Japanese animation. ThunderCats, Gargoyles, Transformers, Batman the Animated Series and I know there is more. but I can't remember them right now.