Clinton, obviously, but Romney 2012 was spectacularly incompetent from start to finish.
Those who voted Clinton don't know what they are talking about. Take out Comey's letter (something over which she had no control) and the same people would say today what a well-oiled machine her campaign was.
Objectively Trump ran the worst campaign. He was an atrocious fundraiser, lost three debates hands-down, was constantly baited into saying dumb and/or offensive things, and changed three campaign managers.
So the person who
lost to the candidate who ran the worst campaign in this time period falls... where, exactly?