The Simpsons is the Jimi Hendrix of cartoons. Newer ones are better, but wouldn't be around without the simpsons trailblazing first. As far as I can recall, the Simpson was the first cartoon to cater to Adult humor. Also, the simpsons became way better when it went from being "the bart" show to being "the homer" show.

South Park is my favorite cartoon for 8 years running!