Taking away from the website:
I did agree with one of the writers who said that King of the Hill jumped the shark when Cotton died. IMO, he was one of the best characters on the show. He reminds me a lot of my grandfather.
I also thought there was never any progression with the characters. The Simpsons is one of the few shows that is able to do this due to everybody staying the same age. I started losing interest about the time Joseph grew about a foot and Connie and Bobby broke up.
Another point from the website. The Cleveland Show will be debuting next spring I believe. That will give Sunday night to Family Guy, American Dad, and the Cleveland Show. Basically, Seth MacFarlane will be dominating Sunday nights.