Interesting that several people have mentioned Nixon along with two Democrats. When Nixon was in office, and especially shortly after leaving, he would not have made many "favorites" lists, but the healing effects of time have treated Richard pretty well. He was a good president who succumbed to his own insecurities.

Mine;

Harry S. - As a native Missourian have to love HT - Another president who was very unpopular, even in his home state, right after leaving office, but who has gained greatly in historical perspective.

JFK - The first campaign - election that I took a real interest in.

Clinton - Another president who would be more revered if not for personal failings.

hon. mention; Nixon, George HW Bush, and Johnson (Vietnam ruined him, but civil rights legislation he championed changed this country more than anything in my lifetime.)