Even though I am totally biased towards Bansko I think you are far better buying a property somewhere that you actually like yourself LynSmith. Personally I have taken a long term view on Bansko and ended up buying there because I also want to holiday there.
If you prefer to holiday in Pamporovo then that is the place to buy for you. The Super Borovets project promises to be very exciting and I am sure there will be many that will make there fortune there but life is not just about money. Surely you also want somewhere that you will enjoy yourself.
Snow cover will always vary, week to week and year to year, some of your clients will have great holidays and some will complain of the lack of snow. You will be the only one who has to live with your decision so pick a place that suits you best - not just what everyone else thinks is the best.