At this late date, one must prioritize one's Christmas movies. And when one prioritizes one's movies, Christmas or otherwise, it's advisable to stick with a battle-tested decade of film-making: the 1940s.
In my not-so-humble opinion, these are the best the 1940s had to offer in the way of Christmas movies. I've triaged them, so read top to bottom, but keep in mind this list assumes you've already seen It's a Wonderful Life (1946) and Miracle on 34th Street (1947), which would probably be ranked at two and four-ish. It seems that those two movies are on television in a continuous loop every year, so if you've missed them, Santa-hats off to you. But go turn on your TV right now, because you're depriving yourself.
(Also missing from this list is Meet Me in St. Louis (1944), which I adore, but which I've shown to too many people who've stopped speaking to me, so I'll spare you -- below are only can't-go-wrong Christmas pics.)
Clearly, The Bishop's Wife is the best Christmas movie ever made because it's the only one with Cary Grant.
As the dapper angel who visits an overworked Episcopal bishop (David Niven) and his neglected wife (Loretta Young) at Christmastime, Grant does that marvelous, unattainable Edward Cullen thing, except not as a vampire.
You may cry during the scene in which the boys' choir in the bishop's former parish, sings, "O Sing to God," but overall it's a romance-comedy-family drama.
Barbara Stanwyck in a comedy comes as close to eating Christmas cookies without gaining weight as you're going to get. She's a treat. If you've never seen Christmas in Connecticut, we're probably not friends, but more importantly, be sure to make it through the first ten or so Stanwyck-less minutes. For some reason, she's not in them, and you may begin to wonder why you've begun a war movie. Don't worry, you haven't. It's a good, old-fashioned, light and breezy, end-of-war romantic comedy, featuring Stanwyck in the only acceptable women's profession for this type of film -- magazine writer.
The plot is appropriately thin -- Stanwyck pretends to have a husband, a baby and a farm in Connecticut to keep her job -- and the cast happily familiar. Sydney Greenstreet and S.Z. Sakall, as Stanwyck's stodgy publisher and lovable uncle respectively, engage in the battle of the bellies. Reginald Gardiner, as always, plays an intolerable boor and very well.
Dennis Morgan as the navy man who wants a home-y Christmas is so dreamy it's odd he didn't have a more prominent career. But he's here, in Connecticut, charming the pants off of everybody with his smile and uniform.
Try not to be nervous as you watch this movie, and just enjoy the Moss Hart and George S. Kaufman-made mayhem. Monty Woolley plays bombastic radio personality Sheridan Whiteside, who falls outside the house of dull but rich Ohioans and convalesces indefinitely. Bette Davis plays an uncharacteristically meek assistant, and Mary Wickes, Reginald Gardiner (again!), Ann Sheridan, Billie Burke and Jimmy Durante run in and out of the living room. It's fun.
Jimmy Stewart follows Cary Grant very closely as my all time favorite actor. Of course, It's a Wonderful Life, rightly, is his best known Christmas film, but The Shop Around the Corner is lovely, won't send you into therapy and is directed by Ernst Lubitsch, so may as well watch it as not.
Please also watch White Christmas if you have a tolerance for that sort of thing. It's from 1954, but I'm getting a jump start on next year's list.