Biden would not be the way to go.
Personally, I would want someone who goes toe to toes with the trumpists.
We have enough Ds who tried to be nice and came out like no backbone morons when the other side hate them regardless and lose the game in long term.
Trump won't be hard to beat if the Dems put up a candidate who can get support from both progressives and independents. The trick will finding the candidate who can draw big numbers from both categories.