I have no preference as to how to refer to this time of year.. I do mostly say "Happy Holidays" though because its just a general reference to the holidays that occur around this time of year based on religion and because it isnt quite Christmas yet. However when it does get close I will begin to say "Merry Christmas". I also do say "Season's Greetings" on rare occasion but overall, I usually just say "Happy Holidays".
As for "Xmas", that doesn't bother me because the meaning of it is widely-known and if you're trying to type out "Christmas" and need some room (say on Twitter for example with a 140-character limit) I'll likely use "Xmas".