It might help to know what you are doing for Christmas dinner. That would certainly influence my selection for lunch that day. That said, (and with the admission that I have never been to WDW on 12/25), I would avoid the MK that day, as I understand that it is a madhouse. Others love the festive crowds. But that's not for me. So if I were in another park, (most likely Epcot), I would think that Norway, Germany, Italy, France, UK or Canada is where I would want to dine on Christmas. Of those, I would opt for an elegant dinner at Bistro de Paris for my special meal on Christmas. Or maybe Le Cellier as a distant second choice for Christmas Dinner. If I went that route, my lunch that day would be something more simple, and I would opt for Rose and Crown. Biergarten is a bit heavy for me to do for lunch if a nice dinner is waiting in the wings.
Hope that made sense.