Though I wrote five years ago that I find the whole idea of a Hillary presidential bid wildly improbable, I say the following as an admirer and supporter of Sen. Clinton. (She's my senator now, after all.)
But here's a reason for not supporting her candidacy that I don't hear often enough: political dynasticism.
George H. W. Bush left office to be followed by two terms of Bill Clinton. He in turn was followed by two terms of Bush's son. If those two terms of the son are followed by the election of Clinton's wife, I don't see where that's a good thing for this country. It ceases to be a fluke and grows into a pattern. It's dynasticism.
Agreed that dynasticism is something be avoided, but in a way this is unfair to Hillary. Unlike George W., who has no apparent aptitude for policy or governance and who very likely never would have gotten involved in politics were it not for the doors his family name opened, it was clear that Hillary had some skeelz before getting together with Bill Clinton. Looking into my crystal ball, which, it turns out, is actually a cantaloupe, it doesn't seem unlikely that Hillary would have gotten into politics on her own, and succeeded.
But could she win? It's true that Hillary arouses more visceral, personal hatred amongst her enemies than probably any other single American politician, but I tend to think that the people who hate Hillary so are extremely unlikely to vote for any Democrat, no matter how Republican-lite they try to make themselves. And I still think that a Hillary win is the only thing that could begin to redeem eight years of W., because I'm not just looking for a win here, I'm looking for a repudiation.