ANSWER:
Voting is not an Islamic thing as democracy goes against the rule of Allah and defies it. However, scholars say that whenever the vote of Muslims may have an impact, we should join and vote to make a difference.
This means that we must vote for the person that would benefit Muslims and Islam most of the two.
If the non-Muslim is better and more fair and less corrupt, we should vote for him as the Muslim ruler’s Islam would not do us any good if he is not practicing and trustworthy.