None of them really excite me at this point for any reason except that they are not Trump. I think Bernie would have handily won in 2016, but in 2020 the board has changed. Warren reminds everyone of Clinton, except more stiff. I have no doubt Warren feels strongly about the working class and middle class, but she expresses it with academic anger that doesn't translate very well (strangely, she seemed a better communicator in that documentary "Maxed Out" from 2006 about credit cards, personal debt, etc.--that was the first time I took note of her).
...
Right now I'm thinking someone young, and bright, who is an extremely effective communicator, and who can rally younger voters and some significant fraction of those who don't vote. I don't see anyone matching that description right now.

Hillary won the popular vote by almost 3 million votes.

If I remember correctly, they gave Trump a 30% chance of winning, and Hillary a 70% chance. That's not the kind of analysis that says she will definitely win. If he puts in 3 lottery tickets and she puts in 7 lottery tickets, picking his out at random shouldn't be completely surprising, just less likely.

@LimitedLight Someone went back in time to hunt a dinosaur that would have died anyway, stepped off the path and crushed a butterfly. When they returned, Trump was president. It's the only explanation.