Bumping from last year!
I especially love the choral renditions of carols. I have a bunch of LPs of the Robert Shaw Chorale, the Roger Wagner Chorale, the Mormon Tabernacle Choir, and (less satisfactory on the whole) the Harry Simeone Chorale. I'd love to get them on CD, but at least with the Shaw stuff, I know they re-did the albums but with the songs not in the same order as on the LP (I only know this from hearing cuts on the classical radio stations), so I don't know if they're abridged or what.
I've always had a soft spot, though, for Nat King Cole's Christmas Song (chestnuts roasting etc.) as far as popular ones go. But I love the religious ones; Gesu Bambino is one of my favorites too.