1. Elizabeth Warren - I don't think she'll run, but she's really the only one who stands out from the field.
2. Tulsi Gabbard - Bernie bros love her, Hillary hacks generally don't mind her, young, strong personal narrative, and easy to make a case for.
3. Sherrod Brown - A good combination of uber-liberal Midwest progressive. Not sure about his charisma, though, and that could hold him back.
4. Kamala Harris - An unknown nationally with a lot of room to grow.
5. Al Franken - A good foil to Trump, but do we really want to stoop to the point of having an election between two old white men who are former TV stars?
Hillary folks hate Tulsi Gabbard more than anything. Most Democrats are opposed to Syrian operatives in Congress.