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 non-traditional: Merry Xmas Everybody. I just love the energy and me and my friends loved to scream "It's Chriiiiiiiiiistmassss" at the top of our lungs when we were young so it has a special place in my heart
Favourite traditional: "Bóg się rodzi" ("God is Born"). People who enjoy Civilization will surely know this song, because Firaxis used it as a theme of Polish civ
I hate when celebrities and "music stars" try to sing older songs "their own way"