MK for me. It's gotten so that I just never eat there anymore- always park hop or go to a Resort for meals. The only restaurants that Ive tried there that I would consider going back to at MK would be CRT (for the atmosphere more than the food) and Liberty Tree. The rest were terrible. Just about the only ones I haven't tried there are Crystal Palace and Cosmic Rays, which I hear aren't too bad, so maybe I'll give them a shot someday.
MGM is next. While I really like all of the park's full service restaurants (except for Prime Time, which I could take or leave), the counter service offerings arn't that good. ABC Commisary was good, but they changed the menu and it hasn't been very good at all lately. Pizza Planet, Backlot Express, and Rosie's are OK, but not as good as anything I've had at AK or EPCOT.