Below, you'll find an argument that the best Christmas movie is Terry Gilliam's Brazil, a film about a bureaucrat trying to survive a dystopian wonderland. Brazil is many things, most of them complimentary. But it is not the best Christmas movie. Not even close.
The best Christmas movie is A Charlie Brown Christmas. It is the obvious choice, but obvious is not always wrong. In that vein, the only other marginally acceptable answers to this question are It's a Wonderful Life (arguably more of a Thanksgiving movie, despite the presence of a Christmas tree) and A Christmas Story. They aren't the best, but they're at least close.
However! Since nomination of Brazil has kicked off a round of bickering over similarly specious selections, let's hear your choice for best Christmas movie in the discussion below. Remember, there's only one right answer—but you can be different degrees of wrong.