Trying to be totally objective here. Of the frontrunners, McCain edged Romney, with Rudy trailing. On points I counted six particularly strong positive impressions each for McCain and Romney, but McCain seemed more likable. (Giuliani had four positive impressions.)
Two of the lesser-knowns distinguished themselves. The best debate performance of all — note, this is judging by who advanced his earlier position the most — was Duncan Hunter, with nine very strong positive impressions and a presidential bearing. Huckabee, who I have made clear I don’t like, was quite good overall and had six specific positive impressions. (Gilmore had five positive impressions, but they did not stick in one’s mind after he finished talking.) Tancredo, Paul, Brownback, and Tommy Thompson faded to the background — although only Tancredo had the guts, correctly, to say he would pardon Scooter Libby. The absent Fred Thompson would have made a strong stand there, I believe.
In sum, I would say the top four finishers were, in order, 1. Duncan Hunter, 2. John McCain, 3. Mike Huckabee, and 4. Mitt Romney. Again, I stress this is not my order of preference, but my assessment of their performance tonight.