Black Christmas, Black Christmas & Black Christmas might be on your holiday hit list for what to watch, but best to choose '74 and '06 and forget about the '09 remake.
Black Christmas (1974) is an old school slasher film and there's some totally 70's dialogue that tells you what era it's from. Amazingly, the police in it are actually competent and give a damn as soon as things go wrong, except for one cop working the front desk. He's the movie comic relief. It can be slow, but there's tension being built as a killer is right under the noses of his victims.
Black Christmas (2006) is a messed-up remake that's fun to watch if you've seen the original as two of the main girls come back as new characters. There's some fun over-the-top kills perfect for the holiday horror season. But it's no masterpiece, behind the scenes the film was disowned by its director and had a lot of meddling of the Weinsteins to make it more gory. The gore doesn't hurt it, but forget tension as it's all about the kills.
Black Christmas (2019) oh jeez, it's PG-13. People complain about how it's got feminist agenda in front of it being a horror movie, but the real problem is the lack of violence and good directing. If you're making a feminist movie in horror, go ahead a blow a guy's balls off with a shotgun; don't bore me with black goo instead of blood. And after just watching the other two, just awful stagnant camera shots. The film was rushed and it shows.
This Christmas remember to forgo the latest Black Christmas and choose the others in the trilogy.