I enjoy all the holidays; I don't consider any of them to be my least favorite, though I suppose Valentine's Day simply because it's not often I've had someone to share it with (though this year was an exception).
Strangely enough I would say New Years Eve is my least favorite. Heck, I'm still tired from Christmas....😴
My least favorite holiday would be Christmas.
As an Iranian, we celebrate most of our traditional holidays. My most favorite holiday is Noruz (our new year) which is in 13 days (YAY) and Yalda. I don't have a least favorite. They are all amazing.