Optimum Nutrition Gold Standard 100% Whey Protein Powder, Unflavored, 24g Protein, 2 LB

I'd actually give this product 4.5 stars if possible, but rounded up to 5 for taste, which is the most important quality. I tried the Chocolate Hazelnut and must say that it is easily the best tasting whey/protein shake I've ever had. I only had one small issue with it: even after a VERY thorough mixing with a standard shaker bottle, there is always a very small percentage of the powder that simply refuses to dissolve. As I'm drinking out of my glass, the accumulation of this residue is aesthetically unpleasant. It is a very minor point... practically inconsequential; yet it is still true.