Wilderness Lodge is my favorite overall any time of year, but for the holidays it is especially magical.
We have stayed at Boardwalk, Kidani (with a couple nights at Movies before moving over), and Poly over the holiday season. For convenience, I pick the Polynesian. For atmosphere and decorations, AK Jambo House is spectacular. Yacht/Beach have great lobby displays. Grand Floridian's lobby is beautifully decorated and has the gingerbread house. Swan/Dolphin is great, too.
No matter where you stay, try to make time to see all the resorts decorated - they're amazing!