I don't think the brand would matter much, but what I would look at is which probiotics are in it. If both brands have the exact same probiotics in them I don't think rotating brands would do much. Are you experiencing gut/intestinal problems with your prolonged use of probiotics? Have you tried naturally occurring probiotics from fermented foods like sauerkraut and kimchi?
"If man made it, don't eat it" - Jack Lallane
People say I am on a "crazy" diet. What is so crazy about eating veggies, fruits, seafood and organ meats? Just because I don't eat whole wheat and processed food doesn't make my diet "crazy". Maybe everyone else with a SAD are the "crazy" ones for putting that junk in their system.