Oh boy, my 2 favorite resorts, but for totally different reasons. When we stay at BC (my ultimate fav....), we enjoy having so much to do within walking distance, such as the entertainment on the boardwalk (beer and sports at ESPN for your DH!), lots of baked goods and restaurants all around. You can rent surrey bikes and enjoy the gorgeous ride around the lake which loops around in a circle passing by BC, YC, Boardwalk and you can watch Illuminations during your ride -- it's fabulous. You can walk right into Epcot countries from BC in 5 minutes and enjoy wonderful meals in the various countries each night if you want. You can also walk or boat to MGM from BC. Lots to do and see. Great pool, not sure about swimming during December though.
When we choose to stay at Poly, it's for the proximity to MK and ease of the monorail, the theme, rooms, and restaurants. The TTC is right there to have direct monorail access to both MK and Epcot. Poly also has great restaurants inside being Kona and Ohana, also the fast-food restaurant is newly renovated and we enjoy the food for something quick. The pool is very nicely themed. The rooms are newly renovated and large, very nice rooms. You can watch Wishes and the water parade from the Poly beach each night.
Two great resorts that offer two different types of vacations. Good luck!