My favorite version of "A Christmas Carol" is from 1951 and stars Alastair Sim as old Ebenezer Scrooge. This is the version I'd scour the TV Guide for every year and stay up late to watch. Usually around midnight on Christmas Eve, if I'm remembering correctly. (Of course that could just be my memory playing tricks on me. Wouldn't midnight on Christmas Eve be the perfect time to watch this movie?
There are different versions of the story that I like for different reasons, but this one is my favorite because of the ending. No other ending has made me quite as happy as this one. Alastair Sim is delightful as the "post spirits" Scrooge. He laughs like a mad man, dances like a fool, and scares the hell out of his maid. He sings as his eyes are opened to a new day: "I don't know anything, I never did know anything. But now I know that I don't know..." You can't help but love the guy.
Here is the ending to the movie. It's 12 minutes, but it's worth it. It'll make you feel all warm and fuzzy.