This is one of those rare instances where you and I disagree but that's okay - I'll protect your freedom to be wrong.
Warren? Absolutely. A polarizing figure with bunch of money who talks about income inequality and once pretended to be a Native American is too easy of a target for Cheeto Jeezus.
Klobuchar, however, actually sounded during the debates (at least from the minimal clips I saw) to come across as the sort of person who could manage a crisis. And her willingness to actually say "no" to a few big government ideas was refreshing. And I also suspect her husband having come down with Covid actually helps her chances since she can pull the old, "I've seen this firsthand."
There's one other thing that deep down I'm wondering this time: will the VP choice REALLY make any difference in how people vote? Historically, it does not. Not one VP candidate selected ever spun the election away from "well, that person would have won but he picked so and so." Granted, the candidacies of Quayle and Palin may have hurt their standard bearers slightly but never enough to say "well, if he'd not chosen X, he would have won" (Bush won a 40-state landslide despite Quayle's having the same public office experience as Jack Kennedy).
We have not had a President die in office now in 57 years. We've had one other case since then of the sudden ending of a Presidential tenure, Nixon's resignation. Probably 90% (or more?) has never lived through the sudden loss of the leader of the USA, so they don't take it into account.
But let's be honest and say they should. They ALWAYS should. But most selections are about, "Who can help me carry state X that helps me win?"
I don't think Biden is wrong for picking a woman; I think he was wrong to promise to do so because he himself imposed a restraint on his options that he never had to do. Now he has no choice without disappointing some vocal activists, who by nature are already perpetually disappointed anyway.