For MK, it depends on our mood. Our favs are:
Casey's on Main Street if we feel like a hot dog and a great view of the castle;
Pinocchio's Village Haus if we feel like an Italian hoagie and Figero fries;
Columbia Harbor House if we feel like a tuna sandwich.
We've tried other things at these restaurants and have not been impressed. However, we loved those specific things.
Animal Kingdom lost Tusker House, which I agree was the best CS in all of Disney. We just returned and tried the Italian panninis at Pizzafari and they were very, very good. We would not hesitate to return there. I'm a stone's throw from GA, and real barbeque is on every corner in my town. That basically left us with either a turkey leg or Pizzafari in AK.
Epcot, wow, just about everywhere has good CS. DH & I usually skip breakfast altogether on our Epcot day and just share small CS items in every country, i.e., chips in England, lamb sandwich in Morocco, brat with kraut in Germany and something sweet in Norway.
MGM - never had anything decent in the way of CS there. Plan for a TS lunch or just do a big late breakfast with an early dinner and make do with a churros or ice cream to fill the gap.