The best argument I heard for her was that she was the most uniquely qualified for the job. She had experience at both the congressional and executive levels, plus she was the first lady for 8 years to boot. That was the argument my girlfriend gave me every time we talked about it and I respected it. But that message got lost when you dug too deep. There were a lot of mistakes made during her time as senator and secretary of state and so they never pressed on the experience platform much. It hurt her quite a bit in the long run.