Biden out of those 3 would have been the best. He'd get a good portion of the minority (waaay more than Warren and Sanders), and will get the working class/rust belt.
Warren should have ran from straight out the gate. Out of HC/BS/MO, Sanders should have been the nominee. Biden would not have been much different than Clinton.
I want Warren but she is a woman and I just know Hillary lost lots of votes due to her sex. I simply don't know if this country will ever accept a female president.
Clearly based on this election Warren would have had no chance of winning, since sexism is still rampant in the U.S.
As for Bernie, I just don't like him as a politician in general. People paint him as this hero for the minorities when he's hardly done anything progressive in his political career. In fact, he's had a track record of working against immigration and gun control. Plus, he's partly why Hillary lost last night.