National Lampoon's Christmas Vacation - Because when he was good Chevy was excellent, and this is his best work. The jokes never get old.
Christmas Carol - I like the George C Scott one myself.
It's a Wonderful Life - why not? Besides I've always had a soft spot for Donna Reed. I think that only Frank Capra could have made this movie without getting too schmaltzy. The acting is, all of it, outstanding. And the screenplay dialog is very well written. So it brings you not just into the story, but particularly with Stewart (but everyone around him also) delivering what many people consider an outstanding milestone of acting on film. Stewart is as good as it gets here, as you don't just see every emotion on his face, and in his body, but in every inflection of every world until it resonates those emotions with your emotions. In very few movies do you really feel not just for the character, but with the character, like you do in IAWF.
And its not some (because Capra was pretty good) all will be well, light-hearted romp. The dark scenes are very dark indeed. And in some ways there is no vindication for evil either (Potter keeps the money, gaining the whole world and losing his soul). No colder world exists then the single line in Potterville: we serve hard drinks in here for men who want to get drunk fast.
It just would not seem like Christmas without it.
And read the Dickens, its a near perfectly written story, much better than any of the movies, which always want to make it about Christmas, then what it really is, a ghost story.