For some beautiful choral pieces, check out Christmas music from Voces8.
Some of my favorite (lesser known) hymns/choral pieces are:
Gabriel's Message
Es ist ein Ros entsprungen
Coventry Carol
Once In Royal David's City
O Nata Lux
Discussion
I love Voces8! Thanks a lot, i will check these out. My favorite song of them is probably "Maria durch ein Dornwald ging"