If the South never seceeded

[True Federalist (진정한 연방 주의자)]

Whether any of these could have been president would have depended on why the South does not seceed.  I just don't see the possibility of how that could be avoided by 1860.  Even if Douglas somehow wins California, Illinois, and the 4 EV's from New Jersey he lostdespite have a majority of the vote in that state and Breckenridge wins Oregon so that the election can go into the House for John Bell to be elected President as a compromise candidate, that will only delay things until 1864.  Once a Republican is elected president, the lower South will seceed.

However, both Jefferson Davis and Alexander Stephens are good possibilities.  They were selected as President and Vice President respectively in large part because of their relative moderation on the heated issues of the day so as to reassure the upper South.  None of the firebrands on the list above could possibly win election as President

[True Federalist (진정한 연방 주의자)]

Suppose the United States includes in 1860 the slave states and territories of Baja California, Chihuahua, Coahuila, Nuevo Leon, Tamaulipas, Yucatan, and Cuba?  Suppose the Compromise Line of 1820 had been set farther north so that most or all of Kansas would have been slave territory without the need to invoke the politically volitile idea of popular sovereignity?  Both of these are plausible pre-1860 changes that would have made the South less likely to seceed.

[True Federalist (진정한 연방 주의자)]

You have to wonder what would have happened had Arlington not been retroceded to Virginia.  If it has still been part of of DC, would that have been sufficient to cause Lee to fight for the Union, or at least not fight for the Confederacy?