I just came across a pretty good piece
on her by Meghan Daum, which I think fits my impressions despite being written by someone with very different political views from mine. It is in large part about the difference between Bachmann and Palin.
Daum's point, although she doesn't put it that way, is that Palin is a flake and Bachmann isn't. Bachmann's beliefs may be mistaken—obviously Daum thinks they are. But she really holds them, really lives up to them, really has put a lot of thought and effort into living the life she believes she ought to live. Which makes her a more formidable candidate, a better qualified one, and, probably, a more interesting person. For details, see the piece.
I should probably add that inasmuch as I had a candidate, it was Mitch Daniels. I agree with Ron Paul and Gary Johnson more than with any other equally serious contender and even know both slightly, to the extent of having spoken at the same event with Johnson a while ago and having met Paul in libertarian circles in the past. But I find it hard to imagine either of them actually getting elected—which is, after all, the usual requirement for the job. I expect that Bachmann's views are similar to mine in some areas, very different in others—and that the same will be true of any serious contenders for the Republican nomination.
I expect that in the next election, as in the last, I either won't vote at all or will vote for the LP candidate as a purely symbolic gesture, assuming that this time they decide to nominate a libertarian.