I use Optimum, not sure how good it is I've never looked into what is the best really, probably a good thing to look into though. I got a 10lb bag of it for a mere 55 bucks though which is pretty fucking good imo (155 servings!). Carbs and fat are pretty low (I think 0g fat and 2g carbs). I buy chocolate and it tastes great. It's loaded with amino acids and all that good stuff as well.