I love basically everything about Christmas, but if I would have to choose a favorite, I know exactly what it would be
I live on a river, and many people who live on the same river I do own boats. During Christmas time people will put lots and lots of lights on their boats (not us, my dad absolutely refuses to lmao) and on a scheduled night in December, everyone will get on their lighted boats (again not us) and slowly drive them down the river, sort of like a parade. Many people from my town enjoy seeing it (and often struggle to get a good view of all the boats), but since my family lives right on the river (aka front row seats every year) it's pretty awesome. My family will often throw a party, invite loved ones, and I will get to invite a couple friends over. My mom usually makes so much food and hot chocolate and it's just so amazing. Often times boats will be blasting Christmas music and people will be screaming stuff like "merry Christmas!!" from the boats to houses and vice versa
Some boats have fancy lights (like a bunch of reindeer... one boat always has lights shaped as palm trees up every year lol), lighted blow-up balloons, and sometimes the sailboat owners will have lights all the way to the tallest point of the mast (just some of the many things people do!)
It's just so magical, and honestly this event never gets old. So there you have it, my favorite thing about Christmas ^^