Obama definitely has the least skeletons. A future political thinker who burst on the scene from nowhere and a rising democratic star. Running perhaps too early but his candidacy is somewhat mandated by the troubled times. And many like myself are now troubled by some of Obama's views as he has defined himself.
As for Hillary, even if she does not have any real skeletons, you will never convince too many nay sayers who would not accept an affidavit signed by God himself attesting that many of the skeletons are made up from thin air by paid Republican conspiracy theory mongers. And the perception is out there, that just one more scandal will finally finish her. Just as we libs have a similar view of GWB&co. The already convinced are always waiting for the great unwashed masses, wallowing in ignorance, to finally come around.
To many like my self, the perception that Giuliani is nothing but a 23.99 carat phony dominates. And who needs skeletons when you have a live Bernie Kerik on your shoulder?
I find it very sad that the GOP could not have come up with a better representative of more centrist GOP views.
Thompson is a little more complex. The fact that he was a Nixon mole during watergate does not attest to honest character. But the honest naivety to believe Nixon was honest
does show some Pollyannia leanings toward personal honestly as an ideal. Of course for those that lean to the center or the left of center in political views, Thompson's positions are repugnant, which hence qualifies him as a Republican nominee contender in a crowded field, and like Obama, lack of executive experience will be a mixed bag.
Like Diogenies* still searching for that honest person** after 3000 years of futility, we voters are similarly searching for a chimera.
* I note Diogenes was a sexist in searching for the only the honest MAN. More modern views can now double the futile search size by including women.
**In respect of the female gender I used the word person instead of the more generic man.