For the food and atmosphere? Cinderella's Royal Table. Hate the princesses though...
After that to me I don't really have a favourite, they're all on par. Except 1900Park Fayre, didn't like that one.
I'm quite the child at heart and I LOVE Winnie the Pooh so my favorite of course, is Crystal Palace. I love the food, the atmosphere, the character, and the fact that it's a buffet!