The best protein powder to build muscle is one that is readily assimilated by the body, but the hard work of building muscles starts in the gym. Rest and diet provide the remainder of the muscle building equation, but only AFTER you pay your dues to the big, core training exercises.
It is so easy for the typical trainee to find themselves seduced by the latest protein powder, believing a whizz-bang supplement will deliver the perfect body in double-quick time. Sadly, the reality is quite different.
Progress, when it comes, is a steady race. More of a marathon than a sprint, muscle gains are made in small, measurable increments that add up over many months and years - this is why fitness should be part of a healthy lifestyle, and not some quick fix.
Consider adding a protein supplement only when you are training hard in the squat, and/or deadlift. Do this - as many have before you - and I guarantee you will build muscle.