Simple question: Out of the 12 Presidents we've had since the conclusion of the Second World War, which one has had the best overall impact for the United States of America, including economics, politics, foreign relations.
I tend to believe that a President cannot be rationally evaluated until roughly 30 years have passed. Time needs to pass for all their actions to fully shake out so we can see if they were reactionary and/or partisan hacks or visionary. That puts Obama, Bush II, Clinton, and Bush I off-limits, IMO. Reagan is borderline, though probably ok to evaluate.
I'd probably pick Truman as the best. As someone mentioned, he made hard decisions at difficult times, and they weren't always popular decisions, but history I think has validated them.
Eisenhower was good, but benefited from prosperous times.
Ford, I think would have been good, if he had a full term.
Johnson was horrible, in the lower 10% of ALL Presidents.
Kennedy was/is overrated, though not a bad President. His pros were motivation and vision, and he might have done well, hard to say. Unfortunately, he gets a pass by many because he was dynamic and popular, and also his untimely and tragic death while still popular.
Carter was out of his league. Should have stopped at governor.
Nixon... I don't know. Overall, ok, did some good things, but some that I cannot abide with.
Reagan. Was a big fan at the time. Now, his star has dimmed a lot in my eyes, as time has passed and things like the drug war and civil asset forfeiture* have taken their long-term toll on the country and society, in general. I cannot forgive those.
*-Reagan started neither, but he did put both on steroids, and used them to ride the "tough on crime" wave of popularity.