My money is on Pamporovo getting the first flurries of snow later tonight. Not sure why but the air in Pamps just looks like it is going open up very soon!!
The resort that will have the largest amount of fresh snow next week should be Pamps. However, my money is on Bansko getting another dump that weekend or the following week that will be pretty substantial and like you rightly mention, Bansko is higher and will therefore sustain that fresh snow a lot longer than Pamps or Boro.