No baggage. A presidential ticket with New Mexico Senator Martin Heinrich and former Missouri Secretary of State Jason Kander would be a baggageless, smart ticket. Yes, two white males is probably not what the Democrats want in today's identity politics era, but they would be formidable against President Donald Trump.
Elizabeth Warren? Too much baggage and a Northeastern liberal.
Joe Biden? Has his time past as former VP?
Heinrich/Kander could be the choice.
Here's my shameless Heinrich TL plug, although, I don't have Kander planned as his VP
https://uselectionatlas.org/FORUM/index.php?topic=277584.0