It’s tough to sort them best to worst, considering that we have mostly done quite poorly in choosing leaders over the past 50 years, but my choices are:
Reagan (by a HUGE margin!)
George HW Bush
Ford
George W. Bush
LBJ
Nixon
JFK
Clinton,
Carter
Obama (by a HUGE margin!)
Note: Obama is one disaster from overtaking James Buchanan as the worst in American history, and he is trying his best to provoke that event.
Carter is the worst of AMERICAN presidents!