This is a list I thought in like 5 minutes so it may not be entirely accurate. I also assumed you meant weekday and Saturday morning cartoons, so I didn't include anime in my list.
10) Ren and Stimpy (the original Nickelodeon one)
9) Super Mario Bros. 3/Super Mario World/Super Mario Bros. Super Show (I liked them when I was a kid, so hush. I also still like them today, although mostly for the wrong reasons.)
8) Mega Man (another one I liked when I was younger, although it's still pretty good I thinks)
7) Garfield
6) Family Guy
5) Rocko's Modern Life
4) The Animaniacs
3) Angry Beavers
2) TransFormers Generations 1 and 2 (still find awesome to watch today)
1) Sonic the Hedgehog (aka SatAM (best North American cartoon ever made, I guarantee it))
I also kind of liked The Adventures of Sonic the Hedgehog (the weekday morning Sonic cartoon, not to be confused with SatAM, although it's also mostly for the wrong reasons today). Chip and Dale's Rescue Rangers was also pretty awesome, along with Darkwing Duck and DuckTales.