Kamala Harris is the most likely pick. She was pushed for by Jim Clyburn, and his endorsement is what handed Biden South Carolina, and he has a lot of sway with black Democratic voters. Passing her over would be seen as a snub to them and that's a major Dem voting block that they can't afford to alienate. But she has negative charisma and the White House basically shoved her in a closet to do nothing so she doesn't have much to show in the way of accomplishments. And she's awful in debates - better than Trump or Biden but anyone who remembers the 2020 primary remembers that the only thing she did was torpedo Biden's standing and then getting smacked around for being a cop.

Gavin Newsome (governor of California) is a big deal in the party but "governor of Commiefornia" is a position with a lot of heat that might not play well in swing states.

Personally I think Dems' best shot is Gretchen Whitmer (gov of Michigan) - midwestern, has a bit of a name on the national stage from being targeted by CHUDS for assassination so she'd have a lot of cred in the fight against MAGA. Josh Shapiro (gov of PA) is floated a lot too, but I don't know much about him.

The funniest option?