I have the answer...
when I'm not concerned with counting calories, I just add a little HERSHEY'S SYRUP to my shakes. As long as I buy a chocolate flavored protein powder, I can just add a little bit of HERHSEY'S and it takes great. Well that's also assuming that you don't mind the extra carbs. But I've been doing it for years and it allows me to just buy cheaper proteins without having to be concerned with taste. A warning though...I have tried using a cheaper brand of chocolate syrup as a substitute for hersheys and it was horrible. I don't know why, but it just doesn't taste the same.