I put do they know it's christmas, as that just is annoying.
Jingle Bells annoys me because it's not a christmas song.
I don't like 'While shepherds watched their flocks by night', mainly because if I'm not singing the wrong words, I'm singing to the tune of sweet bells, and it drives me mad.
I don't like away in a manger or silent night, because they sound terrible, no matter how good you are at singing. Same goes for little donkey. And they don't have descants.
Okay that's probably it for ones I don't like.
I really like most christmas songs (despite what the above suggests...)
I don't understand how people don't like Fairytale of New York. You get to swear at people and noone cares...
But my favourite christmas song is 'Song for Ten', the Tim Phillips version, just because Doctor Who.
I'm going to stop talking now.