For fast food, I'm very fond of Carl's, Jr. Unfortunately, they've got a lousy creative director. The last big ad was a small, mean-spirited thing with a baby near term threaten to cause internal damage if he didn't get jalapeno poppers; now they've got Paris Hilton as a spokesperson.
The problems with using Paris Hilton is that she's not very good-looking, she's got the IQ of a small soap dish, her voice tends to pit glass, and she's just basically trashy. I accidentally caught her show on the toob several months ago and it's clear that she's a whiny, self-absorbed bitch. Her only real claim to fame... well, notoriety, is her appearance in an amateur porn video. I've seen some of it and, honestly, she's not very good at that either. (Life is hard when you're too dumb to f***, I guess.)
Carl's, Jr., has a great product but lousy ads. With any kind of luck, they'll dump their creative director and their ad agency and do ads that have some actual appeal to them.
[end soapbox mode]
Addendum, 6/6/2010: I stumbled over this post when adding labels to the blog posts and I need to add that it turns out that Carl's, Jr., isn't worth eating at for any reason. Carl Karcher, the founder of Carl's, Jr., makes personal donations to anti-choice organizations. His choice to do so and the chain itself isn't making these, but some portion of the profits will go to Carl K., who will give some of this money to anti-choice organizations. He can do that, of course, but it's also my choice to not support this activity with my custom. Here's an article from Snopes.com that gives more detail on this and also on Domino's Pizza.