There's a reason this whey protein from Optimum Nutrition includes the phrase "gold standard" in its name: ON Whey Protein uses only the best protein ingredients.
WHEY PROTEIN ISOLATE
Or WPI, for short. Isolates are generally more expensive, but they're some of the best proteins available. That's why Gold Standard 100% Whey features them as the top ingredient. There's also a splash of ultra-filtered whey protein concentrate (WPC) that rounds out the formula.
ONLY WHAT YOU NEED
Optimum Nutrition Whey Protein has 24 grams of pure protein per serving, with only a small handful of the stuff you don't really need - carbs, cholesterol, fat. Plus, you get a nice serving of glutamine (4g) and branched chain amino acids (5g).
You might not care about mixability now, but you will after you mix your first ON Whey Protein shake. This protein powder instantised, meaning it won't take an hour of shaking to break down all the bits and pieces.