Personal favorite: BoardWalk--excellent services and theme, boardwalk night activiities right at your fingertips (I prefer this resort to any on site), ESPN Club is a good place for sports lovers and for short order dinners, Flying Fish is excellent seafood restaurant, there are two other rerstaurants, a night club, and a dance hall.
BC/YC: these have the best pool on site, Stormalong Bay, which is actually a mini-waterpark and it has a sand bottom. Also here is one of my favorite buffet restaurants for dinner, Cape May (on the BC side; BW does not have a buffet restaurant), which has a seafood buffet (and lots for those that don't care for seafood); YC also has an excellent steak restaurant in the Yachtsmen's Steakhouse. Either side (YC or BC) is a good choice.
Swan/Dolphin: not run by Disney; they are part of the Starwood group (includes Westin); missing some of the Disney touches but don't let that discourage you. Two well run deluxe hotels and a very good pool. Palios is an excellent Italian restaurant. S/D has many discount programs applicable to groups -- like teachers, government employees, annual passholders, nurses--and if you are part of one those groups you can get very good rates even when Disney is not discounting the other Epcot resorts. Note, many rooms do not have balconies.
All are within walking distance of each other and EPCOt and MGM.