"God Rest Ye Merry Gentlemen" and "O Holy Night."
I love them both and can listen to them many times and never tire of them. Two Christmas seasons ago I listened to Aaron Neville's "O Holy Night" many times in a row.
This year I'm listening to versions of those songs by Andy Williams (my childhood favorite, who I saw in concert for my thirteenth birthday), Jars of Clay, Mercy Me, and The Mississippi Mass Choir.