I think I love the Charlie Brown Christmas best for Vince Guaraldi’s jazzy piano score, like the “Skating Song”.
The music is one of the best examples I can think of in any genre of setting the mood for the show. It captures the atmosphere of a snowy day perfectly, and when I hear the accompaniment when Charlie Brown is walking home with his tree, I think of the anticipation of Christmas Eve when I was a kid. Of course, the fact that Linus gets it right, and tells everyone else, is now my favorite part, but the music is still great.