Well, since I make a living out of selling ammunition, I might be able to answer that.
Different types of Norma, and Lapua with the Mega bullet is the best sellers. One reason might be that there is no competition from the US brands in that caliber.
There is also a good percentage of reloads. Norma, Nosler, Lapua, Hornady and Sierra have their fair share of the sales, but as you can guess we always sell more of the cheap stuff, than things like the Oryx bullets.