Whoever is perceived as the "nice" candidate. The Vodkapundit explains.
Hillary vs. Condi? I'd go with Condi as the more "nice" of the two.
Hillary vs. Rudi? Ummm, adultery isn't nice, but Hill may get trumped in this matchup, too.
UPDATE: Is Tom nice enough? He's considering running, you know, even though people in his home state, like, voted him out of office or something.