I really prefer the older stuff made for movie house distribution. Comics got it in the 50's, but animation kept it 'smart' humor that flew under the radar for years. They were allowed more freedom, and for many years less censorship, than almost any medium of expression until tv became common. That was the decline in quality of animation except in 'art' films until computers became available.
While economics will rule for all but the most visionary, many artists have learned to balance the costs with the art. Thus the willingness of modern audiences to accept lesser animation if it is original and the story lines are good. Ren & Stimpy wasn't costly, just original and bold, as Betty Boop was in it's day.
Ed, Edd & Eddy is certainly up there. As is Rocko's Modern Life,Invader Zim, Cow & Chicken, Codename: Kids Next Door, Pelswick, Lilo & Stitch and numerous other quality animations that make it to the small screen let alone the modern cinema.
Any other animation buffs lurking here?
If you have IFC on cable or dish, look for their Russian Masters pieces on odd weekend early mornings. Worth a watch.