I'd say John Quincy Adams. He was one of the few men of actual character to rise to the office of the Presidency. If not for the whole fiasco that was election of 1924 and the resulting emergence of the Democratic party with the singular goal of stopping him from accomplishing anything, he would've been a great President.
I really doubt Hoover would have been even an okay president even without the Great Depression. His politics were basically that of Coolidge, but with an added dash of an eagerness to throw African-Americans, immigrants, and religious minorities under the bus if it meant furthering his own career. What's the basis for the consensus here that Hoover could have been a "phenomenal" president in better circumstances?
Lyndon B Johnson.
If he had been President when there was no Vietnam War raging, which he handled abysmally that had horrendous consequences for America, he could have been a great domestic affairs President. That was his strong suit.
I realize he did have domestic accomplishments, but he could have done so much more domestically without being swamped in Vietnam.
I disagree. LBJ didn't get roped into Vietnam because he was a victim of his circumstances, rather, it was his choice to escalate the conflict because he had a bizarre obsession with leaving an FDR-esque legacy, and he saw winning a war as a component of that. LBJ would actually be a good example of the opposite of what this thread is asking for: someone who was elected with an opportunity to be a fantastic president that he squandered because he was fundamentally unfit to hold a position of power.
