The Simpsons might not be as funny as they were a few years ago, but they're still frackin' hilarious, and way better than that half-assed knockoff Family Guy.
I don't really think that Family Guy is more of a knockoff than it tries to be. Yeah, family guy is also mostly based around a dim-witted father and episodes that have a plot that goes on a tangent every few minutes...but the whole comedy style is different. Family guy is based on parodying television, and everything that goes on in the show tries to make fun of televison moments and cliches.
Simpsons definitely developed their own comedy style, while family guy tends to more parody everything around it, but I wouldn't go so far as to call it a half-assed knockoff.
Also, going back to the comment by MYX about how it would not be the same if Simpsons were uncensored...I kinda think that family guy has often been not as funny lately because they have less censoring of what is on the show...these new seasons are funny, but sometimes I appreciate when shock value is not thrown into comedy.
Anyway...That's my 2 cents...Looking forward to the Simpsons movie...Hopefully it will be something grander than that mini movie family guy did...