WL! I agree that both are great, but if I had the opportunity to go during the Christmas season, I'd select WL because its decorations are wonderful.
My DW and I stayed there in May and had a terrific time. At check-in, the CM upgraded us to a courtyard view room (no charge). We had a blast with a number of CMs there. I became great friends with one of the ladies at the Pin Station near Artist Point -- we swapped pins and stories several times. Our mousekeeper made us two "bunny" toothbrush holders from washcloths after our 1st night and later on left us a little "duck!" And one of the CMs at the bus stop greeted us several times with "Where are you kids going today?" That was a terrific way to head out to the parks.
Great pool, wonderful beach (great to watch the EWP from), Artist Point for dinner, Whispering Canyon for breakfast, Roaring Forks for snacks, a 7-story fireplace with ROCKERS!!!
I could easily LIVE at WL.