In my youth I had a good voice and sang in our church choir.
'Three Kings from Persian Lands Afar, was my solo for a couple of Christmases and is still my favourite.
Nowadays I couldn't hold a tune in a wheelbarow. 
The Carol of the Bells, sung by Pentatonix who make it sound as if there are instruments but it is all a capella.
Having read here about 'The Shepherds' Carol', went to listen to it and that too is lovely.
I also like 'Born on a New Day'.
'In the Bleak Midwinter' made me cry as a child and probably would now and not because winters in Yorkshire were often very bleak indeed
.