In 2008 Barack Obama was a nobody, whose claim to fame was a pretty anti-war speech during the 2004 convention. Then he was backed by George Soros' money and dictates on finance, and who brought in Zbigniew Brzezinski to dictate to him on foreign policy.
Elizabeth Warren has done much more than Obama in the senate, and has made a name for herself in progressive circles by advocating for financial reforms.
Hillary Clinton has done more and has more experience than just about anyone considering running in 2016. Some people love her, some people hate her, and very few are indifferent. As a progressive/libertarian, I oppose just about everything she stands for. I voted for Gary Johnson in 2012 after voting for Ron Paul in the state primary. I would vote for in order; Bernie Sanders, Elizabeth Warren, any Republican (if Hillary was the opponent), Hillary Clinton (never).