bansko is better than pamps for ski area but pamps has a better atmosphere at night in my opinion. remeber the web cam in pamps is right at the bottom of the mountain if it was in the same area in Bansko possibly be no snow there. You will be lucky to get a change so late there will be very little accomodation left for xmas now. there still isnt enough snow in bansko to ski so unless there is more over the next few days not worth paying to move.
I have been to both and would say that the skiing is definately more testing in Bansko. I would disagree about the nightlife there are some cracking bars and Mehanas in Bansko whereas in Pamps it was BJ's or Daks when I was there.The others were really quiet.