Presidents- Great Men(people) vs. Great Leaders

This more a query than an entry.  I am personally an idealist.  Therefore I tend to believe that the means as well as the ends be of equal value or of a higher value.  I would prefer not to vote for Lieberman, and won't, if he somehow got the nom.  I understand the realist side, in so far as it would be of more importance to support someone based primarily on their "electability."

The question I proffer, is this,"Who is the greatest person ever elected President?" as well as the counter "Who is the greatest leader?" I obviously have the my two opposite presidents, and kinda did frame this question around them.  Carter in my opinion is the "greatest" or "best" person ever elected to the Presidency, and Reagan is the greatest leader.  If anyone actually responds to this, remember that the two sides are based along the lines of ideals versus realities, and is not purely based on morals of both sides.