People hated Hillary. She was an unlikable, unpersonable, entitled bitch that an awful lot of people would not have voted for her if you put a gun in their mouth. Biden is a gaffe machine, but he doesn't come off that way. It's not even close between those two in terms of the likeability factor.
In addition, she ran a shit campaign, totally ignoring some midwest states over the objections of Bill and others on her team, because she was overconfident. After Hillary's loss, I doubt very much that Biden will make the same mistakes of overconfidence and ignoring some very important states, which cost Hillary the election, IMO.
This is a different race. Trump has some things on his side for sure, and if the economy holds he has some powerful arguments for re-election, but I wouldn't discount Biden at this point. He's the only one, to me, out of all the dems running that has much of a shot....