Now that it appears that Harris has the nomination locked up, the next step is her choice of a VP.
I think the best candidates are either Mark Kelly or Andy Beshear.
Mark Kelly is a combat veteran (which would appeal to veterans and active duty military), an astronaut who flew on the Shuttle four times, an engineer, and a Senator from Arizona. He’s a good public speaker and would annihilate Vance in a debate. He would also destroy the GOP on the subject of gun control (he’s the husband of representative Gabby Giffords, who was shot in the head by a right-wing nutjob).
Andy Beshear is the governor of Kentucky. He’d help with the Southern vote and with young voters (he’s 46).