Bernie will fire up the base.
Biden will reach Trump voters.
Buttigieg & Klobuchar will speak to middle America.
All candidates have these & other plausible electability arguments. All also have flaws! No one is more of a sure thing than another.
Dukakis in '88 & Kerry in '04 were safe picks to appeal to conservatives. Both lost.
A guy named "Barack" beat the establishment & won. Then a wildly unqualified extremist TV host did the same.
So do yourself & the country a favor: keep it simple. Just vote for who you want to be president. If they get the nomination, great! If not, work your butt off to win in November anyway.