Top ten:
- Washington, for defining the office
- Lincoln, for stewardship through the nation's greatest crisis
- TR, for architecture of the modern presidency
- Ike, for a calm hand during the worst of cold war brinksmanship
- Reagan, for getting the economy going and undoing as much damage as possible that his immediate predecessor caused
- Polk, for fulfilling much of the nation's expansionist dreams in a way that caused a relative minimum of friction (including avoidance of a war with world power Great Britain)
- Ford, for restoring confidence in the presidency after Watergate
- FDR, for his efforts to mitigate the depression (which, given the '38 recession that nearly undid everything, weren't the cure-all many make them to be) and for guiding America away from self-destructive isolationism
- John Adams, for his role in establishing a truly unifying central government (as opposed to the looser Jeffersonian confederation concept)
- Jefferson, for his demonstrations of exercise of presidential powers and prerogatives (although his inept handling of maritime issues and the Embargo of 1807 damn near disqualifies him)
Just missing the cut: Coolidge
The worst ten:
- Buchanan: fiddled while Rome burned
- Pierce: helped build the bonfire
- Fillmore: another northerner with southern sympathies who helped worsen a bad situation
- Harding: inept, and in way over his head-but at least he knew it and said so in so many words
- Carter: naive, inept, and a micromanager-a fatal trifecta
- Tyler: an incompetent opportunist and consummate antebellum southerner (consider he was elected to the Confederate congress but died before taking his seat)
- Madison: provided essentially no leadership to speak of during wartime; his presidency almost cancels his achievements in designing the Constitution
- Andrew Johnson: we all know the story
- Grant: excellent field general promoted to his level of incompetence
- Cleveland: his idiotic Secretary of State Olney damn near got the US embroiled in a war with Great Britain when the latter was at its zenith of power (1890). Hard to comprehend, but true-and all over an exercise of the Monroe Doctrine in South America.
Just missing the cut: Wilson, Hoover
Edit (stealing an idea shamelessly from another entry): a handful, more or less, who should have been president
at some point * but weren't...
1. Charles Evans Hughes: no doctrinaire, rigid Wilsonian idealism at Versailles would have avoided poisoned post-war relations with Europe, and likely would have prevented (or at least mitigated) isolationism in the years afterward
2. Wendell Willkie: probably would have been equally (or very close to it) as effective as Roosevelt, and would have galvanized the GOP into a wholesale Vandenberg-like conversion
3. Nelson Rockefeller: OK, so he never got the top spot. But his nomination would've kept the northeastern, TR archetype Republican from have becoming an endangered species (and I should know).
4. Adlai Stevenson: a thoroughly intelligent, witty man; not at all what Joe McCarthy intimated him to be; would've been a good choice in '60 for the Dems
5. Jack Kemp: Another who never got the nomination. In his case: well-reasoned neo-conservatism combined with cabinet experience and a persona honed by years in professional sports would've made him a fine choice in the late '80s / early '90s.
6. Daniel Webster: had the Whigs nominated him in 1840, the nonsense with Tyler would have been avoided, and perhaps the Whig party might have survived. A consensus-builder, he could have worked out some creative ways at accomplishing expansion much along the same lines as did Polk.
I didn't include Ford, TR, or any other candidate who lost in a given year but were president anyhow. I waffled on Dewey: professionally, he has to be included; personally...well, he was described as "cold" and "egotistic", so he probably wouldn't have been all that personally suited to the presidency. Maybe a superb Attorney General, but otherwise...not sure (and this from an ironclad TR Republican).