Hmmm. Good question. I wrote a fic where Jsng goes all out and makes all of them kiss him for Christmas xD.

But I think it really depends on the holiday? I think Felix and Seunggmin are the ones who go all out for Halloween.

But Hyunjin's the one who does Valentine's Day and White Day. He buys everyone gifts on both days, despite the fact it's supposed to be only one day and the others are supposed to give him gifts on the other. (which they do)

Chan's the one who goes all out for Christmas though, as we've seen with his buying them all iphones, paying for Hyunjin's skincare treatment. He plans it months in advance, asking them stragetic questions about what they want for Christmas, or just things they want in general that they wouldn't necessarily buy themselves.

I also think Hyunjin would go all out for Christmas too. He's mentioned how much he loves Christmas and Winter, so he's probably pulling out the Christmas decor as soon as Nov 1st hits xD