All the same, really
Anyone who gets to be POTUS (or, to a lesser extent, the leader of any nation) has to pass through so many filtering mechanisms that only a particular type of person is eligible. As far as I can see it makes hardly any difference whether (s)he is a Republican or a Democrat, white, black, brown, or candy-striped. One thing you can be quite sure of is (s)he won't be poor. Another is that (s)he has very little freedom of action.
"The Peter Principle was a book that came out in the 60s, maybe the 70s, which said that in a corporation or in some institution, an employee rises to the level of his incompetence and I suggested that in a foreign policy establishment committed to world domination at any price a person employed by that establishment reaches the highest level of cruelty that they can live with. To put it in simple terms, US foreign policy is cruel, it causes great hardship all over the world. The people who carry out those policies rise in the institutions to the point where they reach a level of cruelty beyond which they can't go, where it's too much for their conscience. The cruelest ones claw their way to the top!"
- William Blum (interview with Counterpunch, March 2006) http://www.counterpunch.com/corseri04042006.html
Kurt Vonnegut, Jr. had a more charitable explanation:
"There is a tragic flaw in our precious Constitution, and I don't know what can be done to fix it. This is it: Only nutcases want to be president".