I am not a democrat or a republican. I do not adhere to any ideology except skepticism and rational thought. I simply look at the evidence available to determine my opinion on a particular issue and change that opinion if new evidence warrants it. Unfortunately, Americans are generally not like this.
Since it is the most relevant at this time, I am going to put this in perspective of the US presidential elections. Obama and Romney actually agree on most issues. However, the Republicans constantly rant about how evil Obama is and the Democrats rant about how evil Romney is. It doesn't seem to matter who would do the better job; it only matters which way their political leanings go.
What this means for an independent voter, such as myself, is a plethora of utterly unimportant and heavily biased articles advocating for their particular champion. As media has become increasingly intrusive in our daily lives, the vitriol has grown increasingly worse. Every comment is analyzed to see if a snippet can be twisted to say something abhorrent. Outlandish conspiracies inundate even mainstream articles to the point that they are spouted off as given truths.
So, I have had to determine my own method of determining who is and is not the most qualified candidate. I must know what roles the president plays and what attributes would most help with those roles.
For some odd reason, many Americans and foreigners seem to view the president as a might king whose dictates are law. The reality is that the president makes no laws and only has an indirect influence on laws. As such, the presidents opinion on social matters are rather irrelevant. It doesn't matter if he is a homophobic racist narcissist or the nicest man you have ever met. These have little bearing on how well he will perform the role of president. If you care about liberal or conservative social ideas, pay more attention to congressional elections.
What does matter is the presidents views on national defense, security, international relations and economics. These are the areas where the president actually has a direct influence. When you are evaluating your choice for a president, pick the president based on those topics and how well you believe he can handle those issues. Pick the person who is most capable; don't pick the one you think is nicest.