O Holy Night. I am a baritone in the choir, and baritones don't get solos (Thank God!). At midnight mass there was a fellow in our choir - a tenor - who would sing the opening of each verse and then the choir would come in on "fall on your knees...etc" for each verse. We would sing three verses. He had a very pure tenor voice and would be right on every time. The first time I sang in the choir for midnight mass(30 years ago), when the choir part came, I couldn't sing, I was too choked up with emotion. So "O Holy Night" will always be my favorite.

edit: PS and it was written by a Jewish guy.