Since we have two murderers and one mass-murderer on offer, may I just put in a word for Miles? All things considered, I thought it was surprisingly open-minded (almost sweet) of him not to denounce Michael as an imposter, albeit perhaps not overly strategic. Still, given what we know of him so far, this may be the moral highlight of his career, excepting surprise redemption plot twists.
Mind you, I would sooner meet Miles in a dark alley than Ben any day of the week...