Make a list (doesn't have to be in order), a short (I said short) justification is good. Cannot include any in the last 20 years (history has not written the book on them yet).
Washington- There should be no argument here
Jefferson- For his record, also one of the few times in history when there was a peaceful transfer of power between political powers inside a country (Adams-Federalist/Jefferson Democrat)
Polk- Dark horse, accomplished much in one term- Decided against second term, which I wish more would do
Reagan- ended the Cold War, favorable tax policies, for the most part attempted to contain growth of government
FDR and Lincoln will never make my list- FDR made the the Great Depression worse and gave us today's bloated government. Lincoln started a war that killed over 600,000 Americans- the states were within their right to secede. States' rights have not existed since that war.