A polite political discussion.... that could be tough.
I am a quite definitely a libertarian (or perhaps Objectivist is more accurate) so I was a Ron Paul fan for quite a while. However I am also a scientist and I've realized that I cannot vote for a president who doesn't support science. While this will quite possibly add fuel to the fire of a possibly heated topic, for me the current litmus test of a presidents scientific knowledge an critical thinking ability is their view on Evolution.
More specifically their view on "Anti-Evolution". To keep it fair I can see how his supporters could find good qualities in him, but personally the thought of Huckabee in office spreading twisted fundamentalist christian viewpoints just makes my stomache turn.
It seems the three remaining main players are Clinton, Obama, and McCain. I must admit I know next to nothing of McCain but I'd have a hard time overall voting republican this year. Of the other two I must say Id go for Hillary (Hey she already has experience running our country). She is quite well versed in, and supportive of the sciences.
Obama is quite charismatic and motivational. While I have nothing legitimate to criticize him for I just don't trust him - every time he talks I feel like I'm being tricked and deceived. It frustrates me that most of his supporters don't seem to know much about him or his views. Its almost as if they are hypnotized by his speaking so they just want to vote for him.
So all in all I'm definitely supporting Clinton this year, however I will be looking into McCain's views as already stated I really don't know anything about him yet.
NOTE: to clarify, since I brought it up I am all for having a Christian president; I am a strong Christian. I DONT however see this as a reason to foolishly deny the facts of the world around us. There is no conflict between the creation story and biological evolution.