It all depends on what you like to eat, whether you prefer a quieter restaurant or live entertainment, al fresco or indoors, etc.!
Our favorites in Epcot have been Biergarten (for great live entertainment, a fun beer flight and a buffet with something for everyone - we enjoy the communal seating as it's fun to meet people from other places), the Coral Reef (but only with a good aquarium view - see below), Akershus (for dinner - I could have made a meal of the cold appetizer buffet all by itself) and for counter service, Tangierine Café.
Just a tip, particularly if you go somewhere with live entertainment, a focal point to see, or a potential for good views out the windows: sometimes the quality of your experience can have everything to do with where you are seated, so don't be afraid to speak up if you'd rather wait for a different table! We've been seated at Coral Reef on the top tier, end table, so far from the aquarium that we might as well have been eating at home with a fishbowl in the next room. At Restaurant Marakkesh, we were seated in a far corner behind a pillar, with coffee urns and potted plants totally blocking our view of the periodic live entertainment happening halfway across the restaurant. In both cases, we left sorely disappointed and feeling we'd wasted our time and money (even though our meals and service did not merit complaint), when what we should have done is politely ask if we could wait a little longer and get a better table. We've learned our lesson!
