Personally I’d like to see a joint ticket of Pete and Amy. Don’t care who has which role; they both seem to be the closest choices to rational human beings.
Pete really doesn't resonate with people outside a specific demographic and does even worse than Warren in some head-to-head match-up polls with Trump. But, overall, taking everything into account, of the people running: if I could snap my fingers and one would be President and the other VP, it would probably be Amy (President) and Pete (VP). Biden has bigger positives than either, but also bigger negatives. Bloomberg has the very biggest positives, but definitely the biggest negative of the four sane candidates running. Overall, my choice is Biden for electability in the General without sacrificing any major principles I have.
(Warren and Sanders are both infinitely better than Trump, and I would actively volunteer for either in the GE, but both are also lightyears from the other four in my preference hierarchy.)