Replying to Best Flex for Big Mountain/Freeride Boots

I'm 14 out of Denver and I'm looking to compete in state and regional comps this year for big mountain, and I'm looking for new boots. Price is no problem, I have an internship at a custom ski shop and have got a shit ton saved up for boots this year. I'm riding 2017 Faction Candide 3.0's, I weigh 115, and I'm 5'6".

I went to go try on some boots (Salomon QST 120's, Lange Freetour 130's) and the shop pro was surprised that I could flex 120's no problem. That aside, what is the optimum boot flex for big mountain skiing? OR any other recommended boots for what I'm doing?