First decide
What do you like to eat? types of food-lots of choices from cuisines from around the world to different types of 'American food'
What type of restaurants? Fast food, sit down (plain or fancy), buffet to coked to order.
What is your budget? prices range from theme park pricey for fast food to once in a lifetime (for those of us on a budget)
Where do you want to eat? at the parks or a resort.
And theming is great. Tons of choices. African, polynesian, Floridian, Key West, Atlantic Shore/Beach, New England shore, National Park lodge, southern/Louisiana, Carribbean, etc., etc.

My favorites (in no particular order) are Olivia's at Old Key West, Rose & Crown, Oktoberfest & Coral Reef at Epcot, Whispering Canyon at Wilderness Lodge, Garden View lounge at Grans Floridian (afternoon tea), Chef Mickey's at the Contemporary, Boma at Animal Kingdom Lodge, the food court at The Land ( Epcot again), the Flame Tree Barbecue at Animal Kingdom, the Earl of Sandwich at DD, the Main Street Bakery and the ice cream shop in the Magic Kingdom, Beaches and Cream at the Beach Club.
When my friend and I go we eat at one upscale erstaurant on each trip. And we haven't been disappointed yet.
