Well, I'm not the best to say, as I don't have a lot of experience or anything... but I can tell you why I didn't vote for Romney: in 2008 I held my nose and voted for McCain, after returning from a deployment overseas -- it was then that I found myself stunned/concerned that he might not be a citizen, but the more disturbing thing was that the people in authority turned a blind eye to it (I mentioned to a sergeant that if it turned out he was not Constitutionally qualified the Army would be duty-bound to remove him from office by our own oaths to the Constitution; I received a "shut up private" from him).
In the interim I began to get [more] interested in firearms and in the [New Mexico State] Constitution, only to come across a State Statute (NMSA 30-7-2.4) which was obviously contra-constitutional; I tried to ask those in authority about the inconsistency and only got either redirected (go talk to the IG/state-rep/supreme-court/lawyer) or the statute was justified with other violations of the Constitution such as prohibiting firearms in municipal or county courthouses [the Constitution is prohibitive of municipalities or counties regulating arms "in any way"]. {I finally dropped it in favor of graduating and job-hunting.} But this was a real eye-opener in how the government could, and did, utterly ignore their Constitution -- and when I got involved in investigating a similar situation in SD I found it elaborated, to the point that I now know that I can only challenge some statute as contra-constitutional after breaking it and being forced to argue from the position of weakness: the accused.
Thus I learned the fundamental thought echoing in all levels of government (and any association touching government):
You don't matter, even if you have the law unquestionably on your side you don't matter, because law doesn't matter: we define law as we wish. We are power, and you are utterly subservient thereunto.
And it's from that that I lead back to Romney: Romney is the GOP-E foisting a candidate on everyone else (you don't matter), changing the party's elector-rules to Romney's advantage (they don't matter), having a bus of delegates hostile to Romney conveniently miss important votes because they passed the convention (justness doesn't matter). -- And then there's Romney's record (history doesn't matter), it's seriously surprising how virtually overnight many here suddenly became Romny-will-save-us enthusiasts (principles don't matter), how Romney became Conservative Superman overnight (reality doesn't matter). -- Those who said that the GOP would hold his feet to the fire forgot though that the GOP has done virtually nothing concerning the State Sponsored Terrorism that is Fast & Furious; they've done virtually nothing in slapping him down because of unauthorized military action [remember KMA?], moreover the party has done so astoundingly little in pursuing their stated goals [in the past 10 or so years I've been politically aware to any degree] it's amazing to me that they get any votes.
So, there's nothing about Romney that I could vote for, his only good point was "he's not the other guy."
PS -- That last paragraph, should be read with a nice sarcastic bite on most of those mono-spaced parentheticals.