I want to give you a brief insight into what proteins are best for growing muscle, and why this is, so in order to do this we will look at the term biological value aka bioavailabilty (BV). This term refers to how well the body uses a protein, in other words, of the protein you absorb, how much does your body actually retain?
Well there had always been a clear winner when it came to protein availability and retention, and leading the way was egg, it is one of the only foods that delivers all of the essential amino acids, leaving no limiting amino acids. This meant that egg was given the BV of 100, meaning it was pretty much completely absorbed and utilised. However, they later tested whey protein and found that it was retained and utilised even better than egg protein, hence whey protein was given a BV of 104. To give some perspective, pea protein (as useful as it is) comes in at a BV of 65, soy protein is BV 74, casein is a BV of 77, beef has a BV of 80, and milk protein (being a combo of whey and casein) comes in at a BV of 91.
So in a nut shell, the higher the BV, the better the protein is used and retained by your body.
Llewellyn, W. (2009). Sport Supplement Reference guide. Biological Value. FL: Molecular Nutrition LLC.