I purchase Isopure as it seems to offer the most protein with little or no carb, depending on the flavor you purchase. So far, the Vitamin Shoppe has offered it at the best price. I signed up as a member (free) and purchased in bulk during a sale which included free shipping. To add protein, I mix it with Mootopia Milk (@ HEB) or CarbMaster Milk (@ Kroger). Hope this helps.