Another vote for the Boar's Head Carol. Jon Boden's A Folk Song A Day blog has featured some magnificent carols over the last few days; today's (as I write) is the Holly and the Ivy.

I like to sing Shepherds Arise if I get the chance, and A Maid That Is Makeles (although I change the last word to 'matchless', as that's what it means). And the Moving On Song, although it's as much as I can do to get through the 'seasonal' verse* without choking up. It's a good season for religious slumming - indulging my inner believer!

*The winter sky was hung with stars
And one shone brighter than the rest...