Not quiet old school but old enough that kids today don’t quiet know it, Courage the Cowardly Dog was my favorite. As far as older school, I would go with Scooby Doo.

Tom and jerry by Fred Quimby is the best I think

Being wisened, I really enjoyed sharing older cartoons, and Speed Racer and Tenessee Tuxedo specifically, with my son. In fact, he is the only child that understands older tech in some classes (copper wire line, rotary phones, cloud seeding, rocketry, etc ...) because of TT! Niches really well now that he's all things technology, since he usually researches topics of interest back to invention.

In the other direction there are some incredible anime series out there. Wonderful art, awesome soundtracks, strong stories, great characters. Some of this stuff is as impressive as feature films. Really something for everybody, and worth a look if you like scifi and animation but wrote it off as kids stuff.

felix the cat...tom & jerry...i remember the banana splits.. it was a show that had like 7 different shows in itself.. not cartoons but they had sid & marty, and some more i forgot.
used to always watch battle of the planets g-force

I also liked Count Duckula from the late 1980's.

Mighty Max from the early 1990's, based off of the toys.

Herculoids, Thundar the Barbarian, Johnny Quest, Voltron, Robotech. Dammit, I miss cel animation.

Dark wing duck