Psychopaths, because they have both the knowledge and the personal experience with psychopathy. Obviously not any psychopathic individual can fill such a position, of course, but psychopaths would who have more than the intellectual education and the knowledge gained from studying psychopaths and/or worked with people who know or live with a psychopathic individual, i.e. have a psychopathic family member, boss or employee, etc.
Whereas the psychopath's understanding of what it means to be human in the common sense of the word is largely cognitive, so is the understanding scholars have of us. We are, when it comes to the minority called Psychopaths, the only ones who have that extra specialized knowledge about ourselves, the kind that only can come from experiencing and living that, which we study, from witnessing the subject from the inside, so to speak, and which is always at the very center of the highest kind of expertise, representatives of that very expertise... or we are the only ones who have the potential to be so.
Schooling and education is one side of expertise, and a necessary one, but the other side is the experience of those who live their subject of expertise simply cannot be over estimated. These are the two sides which together make the most complete kind of expertise that can possibly be.It is an element of scientific research which I think has been misunderstood greatly, especially so when talk falls on the psychopath's position in all of this - which so far it rarely, if ever, has. Dr. Robert Hare has said on many occasions that psychopaths, if educated, will use their knowledge against others. And it is mostly true, but he forgets that this statement refers to psychopaths who have already lived through a life of alienation - a position that is known to create antisocial dispositions in many minorities, not only in psychopaths - and who were incarcerated at the time when they were being studied.
Another thing to consider is that it has been confirmed that the background of most psychopaths who become highly antisocial - or criminal - as adults is often characterized by childhood neglect and/or abuse. So - though in my understanding alienation is by far the main factor in respect to psychopaths becoming antisocial and criminal - I think it is apparent that psychopaths, though our character traits are primarily genetic, are susceptible to circumstances and treatment during upbringing, and the extent to which we become antisocial is influenced by it.
'Let Psychopaths Provide Psychopathy Information. (Part 2)' Here.