Our family's favorite CS places would have to be:
MK: We really enjoyed Golden Oak Outpost on our last trip, but I hear they've dropped the chicken sandwiches that were so good. We also like Cosmic Ray's and Pecos Bill's - both have a good wrap sandwich that is a nice change from a burger.
Epcot: We always eat at Sunshine Seasons in The Land. I like the rotisserie pork chop with either mashed potatoes or seasoned rice.
DHS: The CS options here leave a lot to be desired, but we usually wind up at Backlot Express.
AK: Flame Tree BBQ or Pizzafari.
Snack spots:
MK: I particularly like the cafe by the Hall of Presidents. They have baked potatoes, fruit, chips and other items and there are tables to sit while you have a little rest. Aloha Isle is popular here on the DIS for their Dole Whips, but I like the orange/vanilla creamsicle ice better.
Epcot: The caramel store in Germany. Caramel popcorn
DHS/AK: We spend less time at these parks so we don't typically snack much, except for maybe a box of popcorn or Mickey ice cream.