Actually, those are polls. He's not cited by historians as one of the greatest, he's cited by common people as one of the greatest.
"ranking systems are usually based on surveys of academic historians and political scientists or popular opinion."
There are many rankings...
Go to the section scholars survey...
http://en.wikipedia.org/wiki/Historical_rankings_of_United_States_Presidents#Scholar_surveys_details
In the table get down to the 32nd President of the USA (FDR), look at the consistency of his rankings in multiple surveys of scholars...
Lowest ranking: 3, best ranking 1
This is from 1948 to 2005...
"The 1962 survey was also conducted by Schlesinger, who surveyed
75 historians"
"The Complete Book of U.S. Presidents also gives the results of the 1982 survey, a poll of
49 historians conducted by the Chicago Tribune."
"The 1996 column shows the results from a poll conducted from 1989 to 1996 by William J. Ridings, Jr. and Stuart B. McIver, and published in the book Rating the Presidents: A Ranking of U.S. leaders, from the Great and Honorable to the Dishonest and Incompetent. More than 719 people took part in the poll,
primarily academic historians and political scientists, although some politicians and celebrities also took part."
"A 2000 survey by The Wall Street Journal consisted of an "ideologically balanced group of 132 prominent
professors of history, law, and political science". This poll sought to include an equal number of liberals and conservatives in the survey, as the editors argued that previous polls were dominated by either one group or the other, but never balanced."
"Another presidential poll was conducted by The
Wall Street Journal in 2005, with James Lindgren of Northwestern University Law School for the Federalist Society. [5] As in the 2000 survey, the editors sought to
balance the opinions of liberals and conservatives, adjusting the results "to give Democratic- and Republican-leaning
scholarsequal weight."
Franklin D. Roosevelt still ranked in the top-three, but editor James Taranto noted that Democratic-leaning
scholars rated George W. Bush the sixth-worst president of all time, while Republican
scholarsrated him the sixth-best, giving President George W. Bush a split-decision rating of "average"."
Before discarding data provided to you, you might want to read with more care... There was clearly a visible section with the title "Scholar surveys". Which is what I was talking about.
I know you don't like FDR, but come on!!!