I'll tell you what I like about McCain: his stance on energy and the fact that he supports removing the state boundaries for health care. Here's why I won't vote for him:
1) He will push deregulation, even when it is needed most to control the economic crisis
2) He's another liberal Republican like Bush: he'll keep taxes low to get votes because he knows the generation after his (that's us) will have to carry the burden of debt
3) If he dies (and he likely will, with his health and considering the stress that the office of President can cause), Palin will be president
And finally, the thought of him being president that really scares me:
4) He's hot-headed and makes decisions on whims and intuition.
McCain's experience, which he carries on high as his crowning achievement and that which makes him more qualified than Obama to be president, is in part what would drive him to make hasty and risky decisions that could get us into a lot of trouble--something I'd see as a threat to national security. He has the experience, so he can make decisions--that's how Republicans tell it to me, and that's how he'll do it. Someone who recognizes that he has to learn first would be more likely to think before he leaps, a quality which is always desirable in a leader.
Those are the deciding factors for me, though there are many aspects of the Republican way of doing things that I am not particularly fond of. For example, I support both gay rights and women's rights, which I would be virtually voting against by voting for McCain and the Republican party.
One more thing to note: typically, democratic fiscal policies are undesirable in recessionary times, but McCain's policies seem as though they would be even more liberal than Bush's, but with more tax cuts. Either candidate, if elected, will end up either driving us endlessly into debt or raising taxes. I find it hard to weigh them here and would love to hear others' comments regarding this issue.