My favorite one to sing has got to be "Shepherds Arise" (here sung by Poor Old Horse). My favorite one to hear would probably be somewhat less UK-centric that I could never hope to sing adequately myself, like this version of the African American spiritual Rise Up Shepherd and Follow by Cantus, or this truly rockin' verion of ""la cambo me fai mau"" from Provence (this version is sans Christmas content, though; failing Malicorne's version which I can't find online, here's a choral version with the Christmas content in: "La jambe me fait mal" sung by Chorale Jacou). I'm really fond of the Sicilian "Bagpiper's Carol" too, but have to get back to work now...