I haven't answered any of them.
I enjoy receiving cards, but I don't feel comfortable asking people to send them to me. I used to send out hundreds of cards a year, and occasionally sent out quite newsy letters. Sometimes we composed St. Patrick's Day letters, because there's so much else going on around the winter holidays. Maintaining accurate addresses, and keeping track of that many people, became very stressful. I've talked to many people who seem stressed out over sending Christmas cards. So I don't want to make anyone's stress levels rise, just because I like bright shiny objects.
And now, I'm down to replying to cards. I don't send them out on my own, or even take requests. But, I try to answer the cards I get, until too much piles up on my plate, so there are also cards that go answered.
Anyway, that's the current status of me, with respect to Christmas Cards.