Simpsons after season 8 is generally treated as different show, def. don't change your opinion after watching more. Except when you realize it's literally peak cartoon.

Futurama Adventure Time Stephen Universe Earthworm Jim The Maxx Aeon Flux Cyberpunk Edgerunners Neon Genesis Evangelion Star Wars Rebels Bob's Burgers Invader Zim

These are solid gold choices - it get's difficult to watch a lot of mediocre superhero churn-outs after this kind of quality.

If you're willing to go into animated films:

Son of the White Mare (Hungarian) - probably the high point of animation globally. Every frame is a work of art.