Price is a relative thing, it is Disney after all. You will find the prices for fast/table food similar in all parks.
In MK..for quick food we go for a turkey leg at the lunching pad and fries from the mcdonalds fry cart with one of those blueberry drinks at the turkey leg restaurant. For table service in MK..lunch only we eat at Liberty Tree Tavern. We usually eat dinner elsewhere as we are not thrilled about dinner dining options in MK.
In EPCOT..for quick food..we love the cantina in the world showcase for lunch, the portions are huge and the food is pretty good. Plenty of seating available. For sitdown...lunch..we love pretty much all the world showcase restaurants..so depending on what we are in the mood for. The best bang for your buck overall is probably Biergarten in Germany..fantastic buffet at both lunch and dinner, a free show to go with it. The food and service are excellent there.
In MGM...for quick food, we like the commissary or the backlot. Comissary has some different items on the menu, not the usual burgers, and backlot has a very good burger. For sitdown, our most recent experience is 50's prime time (meatloaf and fried chicken), both were quite good, service was great and we even discovered a wonderful new white wine.
In AK...for quick food (well that is all you get there, but it certainly tastes home made and wonderful), we go to Tusker House. We always get the same thing, the rotissiere chicken with a safari amber beer. The chicken is so good and the mashed potatoes and green beans are wonderful.
A previous person is referring to Flame Tree BBQ, where they get the ribs..we have never eaten there. For dinner after AK, we usually head over to AKL to finish the day with dinner at Jiko and a stroll around the lodge, gift shop and savannah.