I've enjoyed Emeril's show over the years, but it does seem to have run its course.
I like Alton Brown's Good Eats, too, but he also is running the risk of overexposure. His role as the "tough judge" on their "Next Top Chef" show was laughable (that show was such a rip-off of Bravo's "Top Chef", which I thought was a much better show).
Paula Deen's shows are just fantasy. Fun to watch, but I'll probably never use any of her recipes. Plus she does get on one's nerves after awhile, especially that "old broad who obviously smokes" laugh of hers.
Rachael Ray's recipes are a little more realistic, but she also wears thin quickly.
Nothing against any of these folks, really. Like most networks, once someone becomes popular the Food Network seems to immediately run them into the ground with overexposure.