Shiela Jackson Lee or Stacey Abrams would be good choices.
Val Demings IMO would be the most dangerous choice for the conservatives. She’s actually got experience and toughness. But again, if Biden laid a hand on her it would not go well on his hug fests.
I've heard a couple of black friends suggest Abrams. You didn't hear this from me, but she would look like his cleaning lady. The optics, not that good to begin with, would be absolutely horrible.