Jam, namely. He likes strawberry, I like raspberry. Also, the importance of correct spelling (I'm a product of spell check). And, importantly at this time, Christmas music.
I'm a traditionalist. I don't mind when contemporary artists cover traditional Christmas songs (I'm looking at you fondly, Sufjan*), but, I don't like it when they mix it up and "make it their own". Yawn.
It's not like I need to listen to Bing Crosby and Harry Connick Jr. for a month straight, but, I like to keep it simple. And by simple I mean traditional:
O Come, O Come Emmanuel
'Twas in the Moon at Winter Time
The Coventry Carol
Lo, How a Rose E'er Blooming