I’d argue that Golden era Looney Tunes isn’t Kids’ animation at all. Sure, it had to be suitable for kids too, but these shorts played before every kind of movie, not just kids movies. Pinky and the Brain (and Animaniacs in general), on the other hand, was made primarily for kids. Yes, they’re enjoyable for adults too, but the primary audience was definately children.
So, I’d definately say that Animaniacs and Pinky and the Brain represents a high water mark for kids’ animation.
(that said - the sad fact is that Animaniacs was cancelled because it was had more adult viewers than kids, so one could argue that Animaniacs wasn’t really kids’ animation either)