In terms of mixability, here is how I rate the ATW proteins I've tried:
Isolate > Blend > 20/30
Isolate ALWAYS mixes well for me. Blend mixes well nearly all the time, but occasionally I get clumps or I get a batch that clumps morethan usual. 20/30 is easily mixable most of the time, however there are always at least small clumps in a 20/30 shake.
As for flavor, I would say Isolate and Blend taste about even. I like them better than the 20/30 flavor. That's why even though the 20/30 is cheaper, I'm sticking with the Blend for the most part now. It is more mixable and tastes better.
Just my opinion though.
Btw, the Cholate Mint in ANY protein type is AMAZING. Whether with water or milk, it tastes awesome. My favorite flavor by far so far. I'm eagerly awaiting peanut butter though. Very eagerly.