They are all beautiful.
We love going to WDW during the first two weeks of December, and have done so several times.
I have to say that the best decorations in my opinion are at Boardwalk. I am a Christopher Radko (mercury glass ornaments) fanatic, and the Boardwalk just reminds me of Radko. There are swags of glass balls everywhere. It is just so incredibly beautiful.
We normally stay at OKW, and the decorations there are good too, in a different way. There are a lot of fish in the wreaths and swags.
The Beach Club is really pretty too. Last year they had a chocolate carousel, as well as a great gingerbread house, though it was not nearly as massive as the one at the Grand Floridian.
We always visit all the resorts to see the Christmas decorations. It will be time well spent if you choose to do the same!