The Simpsons, who dosn't like that show? Well, okay, I know people who don't but everyone by now has to have seen at least one episode, for something that's been out for 15 seasons moving up to 16.
Anyway, my favorite Simpson is Bart. He's the funniest character presently (Homer would win for older episodes, though). Other favorites are Mr. Burns and Milhouse. Just watching Milhouse try to be cool all the time is always hilarious. XD And Mr. Burns is a classic. His feebleness, vocabulary, and twisted mind make for the perfect character to be anyone's boss.
My favorite episode off the top of my head is Homer's Enemy (Frank Grimes episode). Grimes' frustration with everyone and Homer getting away with everything just made it ridiculously funny.