Lesley is no doubt the best choice out of the three to be fair, outside of his weird obsession with killing suicidal people he's quite gentle, he's got a stable (albeit stinky) job, a house, he knows how to care for himself and other creatures, he even has a hobby ! Really, isn't the killing (and untreated traumas and severe issues) juuuuuust a detail ? (I give you a good hour before he gives the killing blow)