A lot of people feel you get what you pay for however I disagree with that... otherwise we would all be using Muscle Tech's stuff as it's the highest priced junk out there.
I used to use Optimum's big bags of protein and always thought it worked fine. Then for about the same price I started using "all the whey" just because they're a sponsor here and I figured for about the same price, why not. I use 1 tub of isolate and 1 tub of concentrate, take one big scoop of each normally or 2 regular scoops of each after a workout. I don't think I was alone in doing this as I see they've now come out with a concentrate/isolate blend. I actually like the taste and consistency a little better than Optimum.
MaxRep
P.S. when I say "junk" up above I'm not actually meaning MT's products are junk, as in no good. I mean that when taking price into account, it's way over priced, IMO.