@3fe52772 
I'm a big fan of Hallowe'en
2nd place goes to Hexennacht
3rd: Winter Solstice 
4th: Summer Solstice 
5th: Christmas
(used to be Halloween, then Christmas, but I've learned a bunch of stuff since I was a kid.)
I'm enchanted by the old tradition of Samhain as the ending of the year, and of Winter not being a season of death so much as dormancy; Halloween as both death & conception, and winter as pregnancy.
Hexennacht is the other thinned-veil celebration, 6 months after Halloween.