I dunno. I could go back to almost any cartoon from the late 90's/ early 00's and it would probably be enjoyable, some of them just had a strange appeal to them. They were either sharp witted, well written, actually pretty funny, or just interesting. A lot of cartoons could get away with amazing things back then (seriously, go look up say, Ed, Edd and Eddy on the TV Tropes Radar section (I'm so sorry I sent you there)). The jokes were borderline adult, but hidden well.
Today it just seems to be "lmao so randum!!" shit, or attempts at "drama" with comedy included. Yes, there were some shitpiles back in the renaissance of cartoons, but the amazingly good ones stood out, and are still known today even if they don't air any more just because they became such icons. I kinda miss some of them. Invader Zim was probably the darkest fucking thing ever, but it was just great, Megas XLR was an awesome deconstruction of the mecha genre, it was dumb, but fun. Dexters' Lab was also a great cartoon, I don't think the same can quite be said for most modern ones.
Megas XLR was the result of a bunch of stoners combining America's qualities and Japan, yet was fucking amazing. Though wasn't it cancelled before the first season ended?
Nick became great again with Legend of Korra, but now we don't know if we're getting a second season or not so exclude that.