Over the years I've liked some of the things McCain did. But I'm not going to vote for him.
You see, I believe in accountability, and in the record of experience. In this case accountability for a record of poor judgement. Support for going into Iraq when it was clearly a trumped up case with no solid evidence, certainly nothing to support killing people (I can say that: I wrote that diagnosis to my friends the day after seeing the atrociously embarassing charade at the UN Security Council). A complete botch of what started as a good idea on immigration policy. Support for the un-Patriot Act and other Bush shenanigans. And choosing a totally unprepared Sarah Palin as a person to have a significant chance of being president within 4 years - something that would surely ruin any chance of reshaping the USA and rebuilding its strength. We cannot have a complicated, powerful nation like the USA run by a person of mediocrity.
No, it just does not add up to good judgement. A record of experience yes, but the experience is that McCain just is not good enough. And one reason why accountability is a good principle is that it removes people proven (or most likely) to have bad judgement. There is plenty of experience that people with bad judgement in the past will continue to make many mistakes. That should be one reason we are alert to a candidate's record. This is not a matter of forgive and forget, this is a case of what you saw is what you would be getting.
I'm not exactly sure Obama is ideal: they never are. Still, he is clearly an exceptional person quite capable of running a brilliant campaign and so far has acquitted himself well in debates. A reasonable chance of being a good chief executive. While holding McCain accountable for his record, the summary of his experience is he is not good enough. We need to elect only the best. The lesson of the past 8 years makes the cost of incompetence starkly clear.