Probably New Years as it’s the only one that there’s some excitement about no matter where one is in the world — even nations that have their own calendar celebrate it as a secondary new year. No use in getting too attached to single-country holidays if you’re a traveler, it just creates melancholy.
Also, because it’s not one of those roaming holidays that’s on a different date each year. Those are too hard to keep track of.
Tiger Riding for Beginners 