In a 2000 WSJ poll of an “ideologically balanced group of 132 prominent professors of history, law, and political science” Reagan ranked 8th among presidents.
In 2012, Newsweek magazine asked a panel of historians to rank the ten best Presidents since 1900. The results showed that historians had ranked Franklin D. Roosevelt, Theodore Roosevelt, Lyndon B. Johnson, Woodrow Wilson, Harry Truman, John F. Kennedy, Dwight D. Eisenhower, Bill Clinton, Ronald Reagan and Barack Obama as the best since that year.
In a 2010 Gallup poll, 74% of respondents rated Reagan favorably.
In a 2014 Quinnipiac poll, Reagan was chosen as the greatest president since WWII by the greatest number of respondents. Same in their 2018 poll.
The sense of his popularity I have fits with those numbers and undercuts the idea it’s a strict partisan divide.