User: Who are the top Presidents of USA
Assistant: Abraham Lincoln, Franklin D. Roosevelt, and George Washington are most often listed as the three highest-rated presidents among historians. 
More recent presidents such as Ronald Reagan and Bill Clinton are often rated among the greatest in public opinion polls, but generally do not rank as highly among presidential scholars and historians. 
Because William Henry Harrison and James A. Garfield both died within their first year in office, they are often omitted from presidential rankings. Zachary Taylor died after serving as president for only 16 months, but he is usually included. In the case of these three presidents, it is not clear whether they received low rankings due to their actions as president or because each was in office for such a limited time that they did not accomplish much.