I believe that I bought The Bells of Dublin because I wanted to hear what Irish Christmas music was like. (This was still back in the BMG days when I was doing some heavy experimentation with CDs.) And I quickly fell in love with the album, starting with the chorus of church bells at the beginning, tumbling through "Il Est Né/Ca Berger" and "A Breton Carol" and finishing with a choral rendition of "O Come All Ye Faithful." But the Christmas Song that I Love from this album, is "O The Holly She Bears a Berry."
This song is basically the "Sans Day Carol" which has some similar elements to the more well-known carol "The Holly and the Ivy." It's often hard for me to decide if I prefer the Chieftains' version or King's College Choirs' "Sans Day." And of course, if I extended my list to 15 songs, "Holly/Ivy" would make it to the list. But I decided for the sake of this list, I hadn't gotten to gush about the Chieftains' Christmas album yet, and so picked their version.