My favorite is "I Wish It Could Be Christmas Everyday", because my dad liked it and we always played it while decorating the tree when I was little. It brings back nice, happy childhood memories.
Least favorite by a mile is "Stay Another Day", which is a simp anthem disguised as a Christmas song, and then "All I Want For Christmas Is You" which is excruciating. Actually, I might overrule that and say I hate "Santa Baby" more, because it's just a gold digger begging for gifts.
Favourite, probably Fairytale of New York as no matter of drunkenness, singing ability or accent you can manage it otherwise does this count as perfect tune for last minute present shopping!
Least: I would say Mariah but I lean more on which ever cookie cutter one they do with the current 'popular' singer/band they do every year..
Yeah, I love Fairytale, too. Forgot that one!
May I also recommend “White Wine in the Sun” by Tim Minchin, in a somewhat similar vein. It’s actually great.