At the top of my must-see list is The Snowman (1982); the animation brings to life Raymond Briggs' illustrated tale of a magical Christmas Eve and is supported by a great soundtrack.
My second pick is the classic stop-motion NBC TV special, Rudolph, the Red-Nosed Reindeer (1964), which teaches us that running away isn't the answer to our problems, and that being different is not a bad thing.
How the Grinch Stole Christmas (1966) is my third pick, because I love Dr Seuss, plus it features the voice of Boris Karloff and is directed by legendary animator Chuck Jones.
Fourth choice is A Charlie Brown Christmas (1965): I just love Chuck and his whimsical dog Snoopy. In this, Charlie Brown has become jaded with the commercialisation of Christmas, but this is charming.
Last but not least is The Muppet Christmas Carol (1992). It may not be animated but I love it anyway, because, hey, who doesn't love the Muppets? Michael Caine is a splendid Ebenezer Scrooge and the cast brings some much-needed laughs to this ghostly tale.
Merry Christmas and a happy New Year to all my fellow Otaku!