It strikes me as rather obvious that Abraham Lincoln would have, if alive today, aligned himself with the Democrats. He was willing to fight wars, but then, many Democrats are too if there is reason enough for war, he was a reluctant, thoughtful man certainly not prone to the my-way-or-the-highway method of GW Bush, and he welcomed, as best he could for the times in which he lived, those that were unlike him in color, religion and so on. He favored an active role of government in driving the economy (this goes back to Henry Clay) and he was by no means a man of overt and stifling religion, much unlike our current caretaker.
I would have cast my ballot for him on both occasions of his being up for election. I want to present to you now some presidential elections before the lines were clearly drawn as to where the parties stand (lines that were largely drawn in the 60s, as the Democrats became the liberal-centrist party, and the Republicans became the party of the radical right.
Here they are:
Lincoln vs Breckenridge vs Bell (1860)
Lincoln vs McClellan (1864)
US Grant vs Horation Seymour (yes you have to one!)
US Grant vs Horace Greeley (yes you have to pick one!)
Rutherford B Hayes vs Samuel J Tilden
Grover Cleveland vs James G Blaine
Grover Cleveland vs Benjamin Harrison (1892)
William J Bryan vs William McKinley
William J Bryan vs William McKinley (1900)
WWilson vs Theo Roosevelt vs Willam Taft