Anything from the first 2-3 seasons, like anything else, once sponsors get seriously involved - all goes downhill.
Personally, I think the show was better when it was based on Bart, instead of all the old men trying to imitate homer.
The show needs to die, but the networks are too gun shy to let a new show really grow. Family guy is getting weak too. The best show currently on Sunday night is *Bob's Burgers*