My favorites:
MK: Cosmic Ray's (QS), Liberty Tree Tavern (Lunch, TS)
DHS: Sci Fi (Lunch, TS)
AK: Flame Tree (QS), Tusker House (Buffet Lunch, TS)
Epcot: So many to choose from...
...Rose & Crown (Dinner, TS - Sunday Roast)
...Les Chefs de France (Dinner, TS - Prix Fixe Meal)
...Tutto Italia (Lunch, TS - Braised Short Ribs and the desserts)
...Biergarten (Dinner, TS - Buffet)
...Kringla (QS - Waffle, Cloudberry Horn, School Bread)
...Pattiserie (QS - any of the french pastries)
...Le Cellier (I haven't been there since it became a Signature, but it was really good before, TS - Filet Mignon)
And at the resorts:
Wilderness Lodge's Whispering Canyon Cafe (Dinner, TS - Canyon Skillet)
Animal Kingdom Lodge's Boma (Breakfast, TS - Buffet)
Polynesian Resort's Kona Cafe (Breakfast, TS - Pineapple and Macadamia Nut Pancakes)
Grand Floridian's Narcoossee's (Dinner, TS - Lobster, Filet Mignon, Dessert) [Signature]