Every StackOverflow user with a reputation of 200 of more has the opportunity to elect a new moderator. The list of candidates looks as if it was chosen from users with high reputation. The voting page says to vote based on what kind of moderator you’d think they’d be, based on their profile page.
I didn’t take this advice. I feel that StackOverflow has a bias towards Microsoft technologies. To even things out, I’d rather have a moderator that works on non-Microsoft technologies. So, I visited each potential moderator’s page and eliminated candidates based on that criteria by looking at their most used tags. I ended up with candidates that I would like to see become moderators, solely based on their subject matter: