The best single protein source if you had to pick one from a scientific point would be Milk Protein Isolate.Its the closest thing to mother milk.It has the highest amount of naturally occurring L-Glutamine and it curdles in the stomach so it has a better sustained release.
But its not as fast as Whey Protein Isolate...
The best protein is a blend..Milk Isolate, Whey Protein Isolate, Egg Albumen, Milk Protein Concentrates, Whey protein Concentrates,and you can also add come diffrent Caseinnate protein in there as well.
All Dr Scott Connely's research on Met-RX was based on Milk Isolate.
If you used the Met -rx when it first came out, it worked like nothing else, why? Because it was mainly Milk Isolates.
The old Met-rx protein was one of the best protein powders ever created.
That is one supplement that bodybuilders, really did use.I know I lived on it...