I think the most important thing in picking a president is not his policy (although it IS important), but his judgment and character. Ultimately, the president does not have ultimate policy authority. He has to work with the Congress to change policy. But, the president alone for all practical purposes makes the decision in times of crisis--to go to war or otherwise deal with foreign threat or use our military. I think the most important thing should be: whose judgment do you trust? Who demonstrastes better judgment? Who better demonstrates intellegence, humility, honesty, wisdom, leadership, courage, love, faith, hope, and character? All of these things lead to better judgment in times of crisis.
Just ask youself if policy or judgment mattered more in the Bush presidency.
Christianity Today did an interesting article last June called How to Pick a President and argued that virtues should be the basis for picking our president, not policy. They focus more on virtues than judgment, but I think their point is similar to mine.