Hard to rank these because they are all so different. I ranked in order of my favorite overall considering food quality, service, and atmosphere. I did not include character meals (they are my favorites).
#1 Yak and Yeti (AK) - partly #1 for their Safari Amber draft beer, one of the few places with draft beer other than Budweiser. Great food, very big portions. Interesting things to look at here. In Asia at Animal Kingdom. Reasonably priced.... Did I mention I really enjoyed the draft beer?
#2 Restaurant Marrakesh (Epcot) - great lunch spot with belly dancing and Moroccan music. Food was different but some choices not spiced so differently if you have picky eaters. Great service, loved the whole design of the restaurant and some neat gift shops. At night, in Morocco, there's a great band (Moroccan Fusion?) also with belly dancing.
#2 Tusker House (AK) - Just a wonderful buffet with lots of different dishes, many with a Africian-Indian flavor, but many "just normal" dishes. Very delicious, not your typical buffet. Bread pudding dessert is out of this world delicious. Convenient location, right in Africa in Animal Kingdom.
#3 Ohana - Dinner Only(Polynesian) - rated high partly because it's at the Polynesian, so stroll on the grounds or along the beach after dinner with a tropical drink from Ohana's bar. Food is great if you're not vegetarian -- mostly skewered meats (pork, turkey, steak, shrimp) all delicious.
#4 Liberty Tree Tavern (MK) - great lunch spot... but will have characters in Jan. while Crystal Palace is closed. Convenient location by the Hall of Presidents in the center of Magic Kingdom. Standard American fare like pot roast and roasted turkey with stuffing -- both just like Mom used to cook it. The desserts are extremely delicious, especially the fruit crisp and shortbread desserts.
#5 Tutto Italia (Epcot) - Probably one of the fanciest restaurants for 1 credit. Top notch service, great wines, delicious food. Can't be beat for food quality. Only downside is there's really no entertainment, at least when we were there. Add some live Italian music and this place would be #1.