For me, Xander Berkley is the only one who could pull off Red John - going by what was seen in Nikita. I'm guessing the dumb Sheriff is an act going by the fact Red John is a Moriarty figure - and more of the Red John aspects will be seen in episode 8 which I think will resemble more of the Percy character in Nikita.
Rewatching s01 ep02, it was interesting that the Sheriff appears out of nowhere in front of Van Pelt. Even Patrick was surprised and confused by it - "he's not supposed to be there". Probably part of some plan by Mcallister - you can see the killer's blue van drive past Van Pelt and Mcallister. Maybe the Sheriff has taken a liking to Van Pelt and wants to protect her from the killers, maybe he knows the killers and wants to get Jane and Lisbon out of the hotel room by forcing the altercation with Rigsby, maybe he simplly is having fun by disrupting Jane's plan. Whatever the motives, it is strange situation and strange that the sheriff's deputy/colleague pulls up soon after like it's all planned.
In s06 ep03, we clearly learn Tom is way smarter than he looks by guessing the dead guy is a pizza delivery man, knowing where Patrick was in the woods, and appearing out of now where again on the church roof to intervene. To me, he wants to make Jane look silly by partially giving himself away by dropping clues but not enough to eliminate other suspects - so the game can continue. He clearly likes toying with Jane in a challenging, playful way. Tom seems to be the only one playing this game - I don't see it in the other suspects; they seem more like pawns or disciples. To ensure the game can continue, he had to kill the guy on the roof incase Jane was killed and the game stops.
The one thing Tom couldn't see coming/plan were the birds in the church tower - the viewers got to see this fear but Jane and Lisbon didn't obviously pick up on it. But for me the nail in the coffin was that Jane genuinely seemed confused and scared by Tom in this episode - I have not seen him like that with the other suspects. For Jane, Tom is a unpredictable and confusing suspect.
We know he is part of Tyger Tyger, likes getting others to do the work, is dark and sinister, likes subtly toying with Jane and yet ultimately wants to be his friend. He is the only intriguing suspect. I'm sure Jane has figured him out and is setting a trap for him, but I don't believe, like some, that he did this many season's ago or anything like that. I am also trusting Heller that the list is real and there are no more major twists or people coming back from the dead etc.
The only other believable ones for me are Haffner and Partridge by physical description facts. But I think Partridge is really dead. Partridge also seems too obvious and I don't think he is someone who can create loyal disciples. It would be odd for Haffner to be Red John when he has been humiliated by Jane out of the CBI. Plus, Haffner shows too much on screen annoyance and frustration at Jane.
Anyway, thats my two cents and let us hope the creator's give us something great.
