Years ago, weight gainers were sold by supplement companies as a way to con skinny kids into getting bigger. They put crappy protein in a sugary drink, made the serving size 32 ounces and claimed it had hundreds of muscle bulding calories! I guess it was better than nothing if you weighed 140 pounds.
Today, people know better -- or should. When I was approached to make BIG BLAST I started with the superior amino acid ratio of the Blair protein formula and then added the super plasma protein , which in a sense, isn't even comparable to normal protein. (Best of the old and best of the new).
Then by adding creatine and NO2 you'd get additional water volume. (Remembering that muscle is mostly water). Add healthy fats and some enyzmes to make sure all the protein is digested and a high glycemic carb to shuttle all the nutrients into the bloodstream and you have a state of the art gainer. THAT is what makes it the best.
Everything else isn't even worthy of discussion. They're all versions of the old style gainers -- cheap protein, cheap sugar and cheap fat. So again, if that's what you want, just buy some bulk protein and mix it Nestle's Quik. What do you think this stuff is anyway?