IMO
Polynesian's Kona Cafe is great for lunch. But if you're looking for more of a quick service, you can't go wrong with Captain Cooks either!
While Grand Floridian and Wilderness dinning options are also great, also think about the time spent traveling from EPCOT to another resort and from that resort to yours for your break.
Kona Cafe lunch is a great option. Often not crowded, good food and decent service (always based upon your server). Captian Cooks is a great QS option as well, and you can get that to go to enjoy in your room while you relax and have some down time.