The Simpsons is legendary and has created an amazing setting and cast of characters over the years.
Futurama is really smart and had been consistently good over the years; it's also created a great and believable setting, has awesome animation, and it's the only animated show that's ever made me cry.
South Park is hilarious and has some of the best uses of satire in entertainment history. Plus, the songs are always awesome.
These aren't on the list, but they should be:
Family Guy has probably made me laugh out loud more than any other show ever, and while the random jokes can be hit or miss, the best ones are classic.
American Dad isn't the best in any one category, but it's just wacky and funny and always makes me laugh.
Everyone should watch Family Guy; it's probably the straight up funniest animated show ever.
I always see them when I can 
