AK-Flame Tree hands down
Epcot-There are several good locations/Electric Umbrella in Future World, Cantina de San Angel in World Showcase would be most popular with us.
MGM-I guess if I have to pick-Toy Story Pizza Planet or ABC Commissary-food just isn't that great there.
MK-Cosmic Ray's
One of my favorite CS isn't in the parks, but in Downtown Disney-Earl of Sandwich.