Mutant Iso, but that is only because I get it for free. ON Gold Standard is fine and cheaper. I only use 1 scoop a day for my protein pancakes, so a tub lasts me a long time.
I just started using powder again for the trip home from the gym. Sometimes when I get home i get busy and don't eat, so at least I have something. I'm using Carnivore now.
On the advice of some of the guys on here, I've been using Beverly Nutrition lately, which is damn good stuff. It can be expensive, but I load up when they offer +30% off sales.