I have a strong feeling of 'deja vu topic' here... but meh...
I just love Ren & Stimpy! The way they interact with eachother and the rest of the world is just awesome! That and... they have Toast Man! Plus rotten teeth! Ghi-hi-har-harr... =P
Courage the Cowardly Dog and Samurai Jack were the most interesting when I was a kid. Everyday after school I'd look forward to watching those. The only way I can watch them now is on the internet. There were also other notable cartoons; Invader Zim, Ren and Stimpy, Rugrats, Ed Edd and Eddy, etc. Most series that aired on Cartoon Network, Disney, and Nickelodeon through 1990-2007.
I'd say Family Guy. I would of said the Simpson's too, but they got really bad. I probably also have a lot of Childhood cartoons but I forgot pretty much all of the names -.-'
There are a lot of cartoons I really like, i.e. King of the Hill, Family Guy, Futurama, Spongebob, Billy & Mandy; but my definite all-time favorite is the original Scooby Doo series, or Scooby Doo, Where Are You? Even though they only made a couple dozen episodes, I'm still proud to say I have them all on DVD and I've watched them multiple times.
I also really liked The New Scooby Doo Movies, but I don't have the DVD set so I just watch them on YouTube when I feel like it.