My DW and I have been to both but if we were to go at Christmas, we'd choose WL, hands down. We saw the decorations last year (we stayed at BC) and they are awesome! Even without them, the Lodge is breathtaking. There is so much to do there, you may forget the parks completely!
WL is so close to WDW, but once you enter the area you feel like you are miles and miles away. It is so peaceful and relaxing -- exactly what you need after a hectic day at the parks.
The lobby is beautiful with a huge fireplace and rockers. Great pool, beach, bikes and watercraft. The geyser and Otter Pond are terrific points of interest.
The lodge tour is wonderful -- you'll learn so much and have fun, too. Ask to be a Flag Family one day -- climb to the top of the lodge to raise the flags and see an amazing view from there.
The Hidden Mickey Challenge from Guest Services is loads of fun!
Artist Point is a wonderful restaurant; Roaring Forks is great for snacks.
While CSR is great and we loved it, WL is in a class all its own.