In MK our favorite sit down lunch spot is Liberty Tree Tavern. The menu is fantastic and the food is delicious.
In MGM we have always liked Hollywood and Vine and Sci Fi. Haven't been to either in a while, but they have never let us down.
EPCOT...we can go almost anywhere for lunch there. San Angel Inn, Biergarten, Norway, Morocco, Chefs de France
AK..we stick with Tusker House..until the new restaurant opens of course
Now, when you are in EPCOT or MGM you also have options over at the boardwalk...Big River, ESPN and if Fresh is still doing that mediterranean buffet (never tried it..but it looked fantastic..the breakfast there is wonderful)