Some interesting choices above.
I'd say I definitely agree with Jefferson. As noted, his work in writing the constitution and Declaration of Independence helped put us on the path to becoming these United States.
I see Dr Guy has included Reagan, and I'd agree to a large extent there. Modern era, I think he was most certainly one of the best, if not the best, given the state of the nation when he took over. I can't say I wasn't scared about his leadership when he was first elected as many people felt he would get us into a war over just about anything, with anyone. He had the cowboy reputation and seemed so relatively unpredictable, you expected that at just about anytime he actually would hit the button and start the strike against the Soviets. But... over time, throughout his Presidency, and looking back later, you realize that he was the great communicator, and he did pull the country out of the Carter mess. Even the *thought* that Reagan was coming into office was enough to scare the Iranians into releasing the hostages they had been holding.
He was able to make massive changes, for the good, to our economy. His tax reform plans fueled one of the greatest expansions ever in the history of the world. And his build-up of the military helped push the Soviets towards bankruptcy and rushed the decline of the U.S.S.R. and the rise of Russia and the separate former Soviet nations.
I could add Kennedy to my modern era list for some things, most noticably the inspiration to get to the moon, and the challenge to the citizens of the country to ask not.... He had many personal issues, was in many ways a slimeball in the example of Clinton, Bill, in his personal life, but he was also a leader in other areas. He'd be seen as a conservative in these modern times, though he ran as a Democrat.
One more I would list is Lincoln. He led the nation through the civil war, and worked to keep the nation together and bring it back together following the war. His words that we now see as the Gettysburg address were so simple, and yet so powerful, and so few at the same time. He was never seen as a communicator, and yet he was in many, many ways.
