BTAS and X-Men both the 90s and the continuation are really good. I also stan 90s spider-man, and if you're a real sicko there's a couple crossover episodes and they share continuity with the (not as good) 90s iron man and craptastic four.

mtv-2 spider-man is worth watching because it's so fucking weird that it exists

all the stuff continuing from BTAS is pretty good

Static shock

simpsons season 1-8 are good and it drops from there pretty quick. some good individual episodes after that and some good scenes or jokes but overall it declines.

Futurama is great but pick one of the finales and stop.

Reboot and Transformers: Beast wars are really cool, especially for how early they are.

Captain Planet

of course.

maybe look up content warnings for them but Heavy Metal is fucken rad other than all the problematic shit and Heavy Metal 2000 is alright if you want more. Love Death Robots does some neat stuff and is kindof a spiritual successor to heavy metal in some ways but it loses a lot by not having the soundtrack.