Biden has lots of good options.
Warren would help unite the party with the progressives and mollify the Bernie supporters. She's also tough, competent and has a national profile, so would campaign well, help turnout, help raise money. Be able to step in if Joe can't make it 4 years. Negatives: old, and REP Guv of MASS would appoint a temporary senator. Liz is good anywhere, but probably best as a Senate leader.
Kamala: Young, tough, some national presence, would help turn out minorities. Hopefully women too. Negatives: from CA, not that big a national profile. Might help with CA fundraising.
Klobuchar, Whitmer, the Tammys -- white midwesterners* from the key region. Whitmer has looked strong and competent and willing to tangle with Trump.
MINN, WIS, ILL. Klobuchar and Baldwin seem a bit bland and overly moderate to me. (female Tim Kaine's). And a moderate Dem is basically a Rockefeller Repub of yore. *Duckworth with the most compelling personal story, but ILL is only close to the action but not a battleground state. And it might take some balls/idiocy to select an Asian during the rampant China bashing.
As for picking a female pol from the Midwest, I'd probably go with Whitmer or Klobuchar since they have the national profile and have been in the fray recently.
But really I don't know much about any of them.
Anyway, those are the 3 potential paths Biden can go down. A progressive, a young black woman, a moderate white midwesterner (or Duckworth). I'd guess that since Biden committed himself to a woman, he'll probably go the safe moderate regional route. With Kamala having an outside chance. I'd be very surprised if he went with Liz. I think Biden will take the traditional approach of trying to win a region or state with his Veep.
Poll
5 (45.5%)