Ooh ... way too many to choose from.
The good old Looney Tunes and Merry Melodies are always fun.
The "Duck Dodgers in the 24th 1/2 Century" series. Which was a great sample of a spin-off done right.
Rick and Morty, RWBY, Venture Brothers, Robot Chicken (does that count as a cartoon ... it's stop-motion) ... yeah I'll take my humor like I take my coffee: dark and bitter.
But also a lot of series for the younger audiences that are still enjoyable for older audiences, like Gravity Falls, Avatar, the occasional SpongeBob, Ducktales, SW Clone Wars, SW Rebels, etc, etc