Well I have ON's and Pro Rated's chocalate which I like, but I always drink those with 3/4 no fat milk and 1/4 water (my wake up and before bed shake).
I also have ON's cookies and cream and Pro Rated's vanilla, but I always drink that with orange gatorade and water (postworkout shake).
I tried ON's mint chocolate, but I jus remember that mine didn't mix well at all, but I think it did taste pretty good. Also their strawberry, which wasn't very good.
I usually buy Pro Rated at costco $20 for 6lbs, best deal I found.
My bro takes CytoSport whey protein in cocoa bean flavor, thats pretty good too and mixes well. Its the sweetest powder I have ever tasted.