I'd pick the one that polls the highest against Trump whether I like them or not. That was the only reason I was supporting Biden in the past. If I could go back in time and do a real primary and pick someone based on who would run the country the best it could be a million people (Bernie, AOC, Buttigieg, etc), but the thing that matters to me most is who stands the best chance against Trump. A milquetoast do-nothing dem is a mile ahead of Trump 2.0 + P2025.
That's pretty much the entirety of the DNC platform now, "Not Trump". I went to the Democrat's website last night to actually read the platform and the first thing I saw was a huge banner with Trump's face.