Good Eating.
I can never say it enough. For me there's only one place to eat in the 'World:' The Hollywood Brown Derby at the Studios. I have two more words for you: Cobb Salad. It's fantastic! Get it with chicken, excellent. I also recommend their grapefruit cake, and I don't like grapefruit. Toy Story Pizza Planet and Backlot Express are both good for something quick at the Studios.
I also really enjoy San Angel Inn at Epcot in WS. The food is good as is the atmosphere. Try the queso fundido, excellent, even if it is only an appetizer. I also really enjoyed The Coral Reef at Epcot, but I thought it was a little expensive. I've heard really great things about Restaurant Marrakesh in WS's Morroccan pavilion. For a quick meal hit the Liberty Inn in the American Adventure pavilion.
As for MK and DAK, I usually only eat at a counter service restaurants. Usually Pinnochio's in MK, my favourite double cheeseburger in WDW, though I also really like Cosmic Ray's Starlight Cafe. At Cosmic Ray's look for Sonny Eclipse, the biggest little star in Tomorrowland. I usually eat at Restaurantosaurus in Animal Kingdom, if I eat in that park at all. They used to serve McDonald's fries, but I don't know if they still do. We had a quick breakfast once at Tusker House Restaurant & Bakery in Harambe Village, it was pretty good. However, I don't think they serve dinner, only breakfast and lunch.
I've never eaten at any of the resorts, but I hear Boma at AK Lodge is excellent.
For a quick snack in MK, try a pineapple whip in Adventureland.