I'd say Vail or Copper, as far as dispersing any crowds from the holiday week. Looks like Back Bowls should be pretty good, as there was good snow last couple of days and maybe a few snow showers today, with cool enough temps and clouds to keep things soft. Then warmer and sunnier on Wednesday.
With Vail on a holiday week you want to start early and drop over the back side pretty quickly if you don't need too much of a warmup. Maybe straight back into Sun-up and then a run or two in Teacup or on Ghenghis Khan and then catch one of the first chairs into Blue Sky if you want to ski there. Then maybe make some time for a few turns on the west side of Siberia if the snow is good. Then get back up to the top for a quick, early lunch (11:15ish) before everyone heads inside, and then back out in the bowls while the holiday crowds are eating.
I don't really know A-Basin as well, but it doesn't tend to be too crowded, and I doubt it will get too many Prez Week gapers.
Stay far, far, far away from Breck and Keystone this week, as they are full of families visiting from the east coast for the holiday week. Will likely be very crowded. Vail will be too, but it's just so big it's possible to work the mountain and stay away from the worst of the logjams. I'll be skiing Friday, so I am hoping to start early and avoid the craziness as much as possible.