Most of them. Christmas IS the most wonderful time of the year. What better thing to do during the darkest, shortest days of the year, than have a Festival of Lights?? Brilliant idea. And it's so cozy.
Easter is an amazing holiday if you go to church. I couldn't care less about the eggs and bunnies (tho it's fun for the kids) but the celebration of Jesus' death and resurrection gets me every time. It's a very meaningful time starting with Ash Wednesday and Lent.
Halloween, I hate the ugly stuff but pumpkin carving is great, and celebrating fall and trick or treating. Thanksgiving is the yummiest meal of the year. Don't give me no lines about 'but we are thankful to God EVERY day.' Shoot, even the Hebrews had thanksgiving and seasonal festivals. Witnesses, they have NOTHING. They have darkness. They don't mark the seasons with anything. Mother's Day and Father's Day are nice, and no, it doesn't have anything to do with goddess worship (and Father's Day was supposed to be what pagan thing exactly??)
Birthdays are important milestones of life. Most depressing thing is to be a kid witness and not get to celebrate your birthday. Thank goodness there were a few families that would rebel and cook their kid their favorite meal on that day, at least.