The results of an action are what matter most. So who to vote for is determined by what their election will result in, and that includes what they themselves will do with the power, how other politicians will interact with them, how they will be perceived by foreigners (not the biggest factor, but it does have some relevance), the likely reactions of opponents, and so on.

Your imaginary situation doesn't have enough information to make those determinations. To answer your underlying question, I don't see a good way of formalizing into a systematic process the balance between personal flaws and likely actions.