@rubenjrc: It sounds like you really haven't seen a single episode of the Simpsons.
Homer and Peter are both naive morons most of the time, but Peter is also bright at some points.
Meg and Lisa are both very different characters. Meg is a stupid teenage girl who wants to hang out with all of the dumb popular kids and will do whatever it takes to fit in. She's also obsessive and nobody likes her. Lisa on the other hand is a very smart and knowledgeable individual with bucket-loads of talent and creativity. She is the brains of the Simpsons family.
Chris and Bart are also pretty different. Chris is shy, fat, and his hobbies include just sitting back to draw. He's also a bit of a nerd. Bart is a rebel and a prankster. He's outgoing and trolls people for the lulz.
Lois and Marge are basically the same character, but Lois has a better sense of humor and is probably just a bit smarter than Marge is.
Stewie and Maggie are polar opposites. Maggie DOES NOT plot world domination. She just sits around and sucks on her pacifier. She's hardly a part of the show at all. Stewie is extremely intelligent, well-worded, and dreams of the day he kills Lois and takes over the world.
Family Guy also has the deciding character that puts the show just over The Simpsons for me: Brian, the family dog. Clever. Witty. Awesome. When Lois can't hold the family together, Brian usually steps up to do so.
Also, yeah. I'm one of those people that thinks the Simpsons stopped being funny a long time ago. I love most of the earlier seasons, but the formula is so tired and it just doesn't work for me anymore. Family Guy has at least stayed consistently funny since it's inception. By the second episode, the show has shown you that it's a one-trick-pony with it's scenes that don't advance the plot at all (ie. "He's treating me worse than that jerk, Christian Bale"), but it keeps that trick fresh with plenty of pop culture references and snarky unpredictable humor. I've been watching The Simpsons since I was 5, but today I prefer Family Guy.