Favorite President who was defeated in the general election

[Badger]

I'll say John Quincy Adams  Given the leadership he gave the fledgeling abolitionist movement. After that I'd say Carter, but it's A distant 2nd.

[Aurelius]

John Quincy Adams was in my estimation the single best diplomat and SoS in US history, and a legendary member of Congress for very good reason, but he still was a failure as President. The very same aspects of his character - bullheaded stubbornness, fierce independence, and rigid insistence on sticking to often idiosyncratic principles - that served him so well in those other roles fundamentally undermined his Presidency, due to his complete unwillingness/inability to make compromises and form coalitions to enact his agenda. This is a surprisingly tough choice and I'm tempted to go with J. Adams (in spite of the Alien & Sedition Acts, and even though I definitely think Jefferson winning in 1800 was the better outcome), Taft (although I know very little about him), or Ford.

I'm judging strictly on presidencies, not on pre- or post-presidential careers.