Epcot - Mexico QS, United Kingdom QS, or Japan QS are our favorites
MK - Columbia Harbor House and Pecos Bill's have the most unique options, different items than your standard burgers and chicken fingers. We like the atmosphere inside Pinocchio Village Haus best.
DHS - I guess my vote would be PizzeRizzo, which isn't saying a lot. The pizza is mediocre at best, but we like it and the atmosphere better than most of the alternative options. Whenever possible, DH and I will boat/walk over to Beach Club for lunch at Beaches & Cream. We've also even taken a bus to Disney Springs after leaving the park just for more options.