Bruno Heller has said that Red John is not a "pathetic loser who is hiding out in a basement somewhere", and that Jane is "not fighting the Green River Killer. He's fighting Moriarty."  If we take that to be true, which I'm going to now

RJ cannot be the local cop pretending to be dumb, or the forensics guy who loves gore or the lower level FBI guy trying to make headway in a police mafia

POWER HIERARCHY from GREATEST to LEAST

1.  STILES:  he's been the most obvious and formidable player from the start but also he's OLDER, seemingly meek, and HELPFUL to Jane, so we discount him but if we're looking for outward appearance of education, class and power -- it's him
2.  HAFFNER:  I only put him this high because of his association to Stiles, who would seem to help and protect him
3.  BERTRAM:  He's Director of CBI -- BUT he answers to high authorities and sweats bullets doing it
4.  McALLISTER:  he might be Rigsby's personal Moriarty, but he's not Jane's!
5.  SMITH:  a Tyger Tyger henchman in the FBI and a killer but lacking slightly [insert sarcasm] in the social graces
6.  KIRKLAND:  DEAD -- but alas -- there's a TWIN -- who I think AT BEST would be an RJ HENCHMAN, not RJ himself because the Kirkland brothers grew up in a desperate wasteland of violence, alcoholism and suicide of their mother.  Hardly likely these boys would be afforded opportunities or education.  Bob Kirkland got into law enforcement, something a person from his background, similar to Rigsby, can do to better themselves when they come from nothing.
7.  PARTRIDGE: DEAD -- who of ANY of these people are going to take orders from Bret Partridge? LOL  Partridge is the one taking the orders.

I think it's interesting that the TWO MEN who likely have the LEAST POWER and authority are KILLED FIRST  

BRET STILES is the only one on that list that fits the bill of being a formable nemesis, though now weakened [by age or illness] and on the run from the FBI.  So, I'm going back to an older theory that I had that BS is RJ and he's had helpers,  perhaps the lower level guys like Partridge, Kirkland Twin and Smith.  Not sure though if I see Haffner as an RJ helper.  I think Stiles could be RJ right under Haffner's nose and he wouldn't know it LOL
 
Other than STILES -- the most powerful man on the Mentalist that we've actually seen is OSCAR ARDILES