I think terms like "Worst" or "Best" betray a very limited scope of thought on the issue of leadership. They present a list and don't even get into a definition of a highly ambiguous and abstract relative term such as 'good'. What is merit in this context?
With regards to the positive or negative benefit for the society at large of a presiden'ts legacy, it's impossible to judge current presidents versus past ones. There's a heuristic that says people tend to remember the good, forget the bad. Therefore, historical figures and ages always appear better than the here and now, where people obsess on the negative, particular in today's viewpoint.
There's a reason why historians traditionally used to wait 20 years before commenting on the legacy of a governing leader, and wise ones still do.
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