I swear by InfinitNutrition. You can customize your sports drink: more or less calories, electrolytes, protein, flavor, etc. It sounds really foofy, but for me, it works better than any of the others.

When you go to the site you can buy an already set mixture or you can fill out a quick questionaire that helps set up a blend for you. You can then customize it from there. My mixture has less flavor than suggested with 1.5 grams of protein per 20 oz. bottle.

It runs about the same price as Hammer's products.