MK- Have only tried Peco Bills. Good burgers and fixings bar. Want to try Cosmic Ray's. In terms of a snack place, Sleepy Hollow is excellent for ice cream sandwiches and of course, funnel cake.
AK- Pizzafari. We want to try Yak and Yeti on our next visit.
MGM/Hollywood- None.
Epcot- They're all soo good! Boulangerie Patisserie in France is fantastic. Good pastries, sandwiches, quiches, croissants, etc. The counter service in Japan is also very very good. Tangierine Cafe provides lots of tasty food in each of its servings (good value). The quick service restaurant in The Land pavilion has lots of choices. I could go on and on....