Reverend Alberts is my favourite, because seeing a holy man running around shooting things raises some interesting personal and moral questions.
Killing humans is wrong, obviously. A Reverend would never kill even an animal. But are clones human? Most of the specimens can firmly be placed in the non-human camp, but do they have souls? What if they see US as the dangerous, psychotic menace? Obviously the Reverend has to justify killing somehow.
Maybe he acts as a medic. That seems to fit best with him. Healing, not killing. Or maybe he is a sharpshooter, figuring that a bullet to the brain is a merciful end to the short, painful life of a specimen. Or has he gone completely insane and begun to wield a rocket launcher, eschewing the tenets and beliefs he has held up until now?
TL;DR - Looks cool, feels cool.