I generally hate the idea that Family Guy is a Simpson's ripoff, on the basis the if you say that, then every animated TV show about a family with a not-so-bright father is a ripoff of the other, the exception being The Flintstones, which in itself was an animated ripoff of The Honeymooner's set in prehistoric times.
I prefer Family Guy over The Simpsons. Yes, it's getting old, but goddamn, the jokes that Family Guy come up with are hysterical, I don't care how many times it's beating a dead horse. The Simpson's on the other hand, at least in my view, looks like they're trying to convey some kind of moral message, followed up with a side story of somebody's zany adventure.
And also, to the people saying that the Griffins are a ripoff of The Simpsons, let's examine the family members:
Homer vs Peter: Both are idiots. Both are drunks. Peter embraces his male neighbors, Homer hates his. Peter is a prodigy when it comes to 80's pop trivia, while Homer just fucks it up somehow.
Marge vs Lois: Lois is incredibly adventurous, promiscious, and open minded, while Marge just sees something she doesn't like and does that "mmmmhhhhhhhhh".
Bart vs Chris: One's 10, the other's 14/15. Chris stays out of trouble, Bart worships it.
Lisa vs Meg. Lisa is a genius, Meg is obbsessed with her social life (or lack thereof). Lisa eventually has sex as implied by future episodes (...Milhouse....Ralph ), while Meg becomes a transgendered.
Maggie vs Stewie. Ok, both are infants. One just sucks a pacifer, the other is psychotic and brilliant. Yes, ripoff indeed.
Santa's Little Helper vs Brian. .....nothing should be said.
So then, must The Simpson's have the absolute monopoly on being an animated TV show where the starring roles is a family? No, it shouldn't. Despite ER still running, I have yet to hear how House rips off of it.
If you like one and not the other, fuck it. They don't rip off of eachother, just let it be. And you're going to cry ripoff, let's remind ourselves that how many themes in literature are constantly recycled off another one? Exactly.