Ooo, that is such a great and succinct list of what you like in a beta! I am in complete agreement, no surprise. :D And, also very much agree on having multiple betas to get different POVs and strengths. I've definitely had betas give me feedback that I instinctively didn't agree with, but then was able to run by my other beta to get their thoughts and see if I needed a step back to get perspective on the story, or if it maybe really was just one particular beta's person feelings. I try and be aware of that in my own betaing, and will often make notes letting the person know that my comments on particular parts might be motivated by personal preference and that they should take it with a grain of salt.