I know this is an old thread but I found this vid interesting:
http://www.youtube.com/watch?v=QcQ8E3y7-Uc
It's a comparison between the animation studios of Batman: TAS. Why can't someone make a vid like this for the old TMNT toon? That'd be awesome! Anyway I noticed with BTAS the artwork was always different from episode to episode, just like in TMNT. And as always, the Japanese studios always had the best artwork.