Hello everybody!
As the end is coming, I'd like to share some thoughts after reading all your interesting theories.
Firstly, for me, RJ is an important character in a TV show, so I would like to see him as someone important in the (police) organization, for instances same grade as Haffner or Bertram or Kirkland. I think Partridge and the sheriff and the cop are a little low in the food chain and I'd be disappointed if RJ is one of these. Moreover, as the story goes, RJ seems as intelligent as PJ and honestly when looking at these 3, I don't see any sight of a brillant/intelligent mind.  
Secondly, I think RJ might use the tatoo to blame the Blake Association: who in earth would reveal his tattoo on his shoulder when meeting with the female detective? I mean you go to a meeting and dont wear a shirt ? because it's the only way for others to see your tattoo! This leads me to think that RJ might or might not in Tyger Tyger circle but he wants to use this secret organization to serve his purposes. The others in the group dont know who is RJ and like Jane they want to find out who he is. So this leaves out the 3 tattoo cops
Thirdly, IMO, Stiles is a little old and even though his character fits RJ's description, he isn't strong enough to pull off these kind of killing. In the first espisode of season 6, RJ didn't kill Lisbon so it might mean that she is an asset (bugged) or RJ has a thing for her. 
For all of these reasons I think RJ would be Haffner. If it turns out that he is Kirkland, I'd be happy as well :-)

Am i the only one who felt sorry for Kirkland?

He was only trying to avenge his brother and he got shot in the back! 6 TIMES!!!
Yes he kidnapped and tourtured people to get answers but are you seriously telling me that Jane wouldn't do the same if he thought someone had information on Red John?

Were getting close to the big reveal and we all have one question in mind...
WHO IS RED JOHN?

As far as I remember, Red John was the first one to mention Tiger, Tiger
to Jane. He must have known that Jane might bring this topic on the
table at the CBI.

Why would some (high) member of tiger, tiger want his own secret organization to become an open topic in the investigation?
He probably wouldn't. That's why I think that Red John might have used
Tiger, Tiger but he is not a member. It was even hinted by one of the
writers, I think, in an interview, that if there are too many people with tattoos, RJ might not have one.

Taking all 7 on the list into account, this leaves us with Partridge (we don't really know if he had a tattoo), Haffner, Stiles and Kirkland.

It was also said in interviews that the actor was surprised when he was told that he was Red John.

(The
actor of) Partridge said he played him as if he was Red John all the
time. So he would not have been surprised. The actor also confirmed that
his part was over. Partridge indeed is dead.

McDowell (Stiles) said in an interview that he though he was Red John.
So he wouldn't have been surprised either. So it is not Stiles - even
though I'm not sure if he is really dead as it might be that nobody died
in the explosion.

Why was Partridge killed by Red John? It was
probably necessary to have someone in the CBI confirming the death of RJ
and so Partridge needed to be replaced by someone under Red John's control.

So this leaves us with Haffner and Kirkland.

Someone
had a theory that Haffner actually IS Kirkland (Michael Kirkland).
Because he changed his appearance when he turned into Red John. A bit
far fetched but sounds kind of cool.

But we know that Haffner has
a crush on Lisbon, which would also explain why she wasn't killed in
episode 1 of this season. Haffner also fits to every description of Red
John, he has ties to Visiualize, the CBI/FBI and he is kind of a regular
guy (at least compared to suspects like Stiles or Bertram), which Bruno Heller said RJ would be and we would probably be disappointed about him.

We don't know much about Haffner's private live and past before CBI/FBI, so anything is possible.

http://www.hizliresimyukle.com/oUU2

http://www.hizliresimyukle.com/oUUA

There are only say...2-3 suspects I feel. 
Kirkland - Dead 
Stiles - Dying/Dead (and he's too old to fit any description anyway)
Bertram? - Way too obvious if it was him. It wouldn't fit the Red John legacy anyway. Besides, Red John isn't even supposed to have been revealed until next episode.
Reede Smith - He's in jail. I agree with Jane when he said Red John wouldn't open up like that. If he was RJ, he was almost killed by Tiger Tiger several times, and RJ wouldn't let that happen.

Partrige? In the beginning I thought he was 100% dead. Then I read some theories and thought maybe... But no. Cho saw the body, Heller said he was dead, and it just seems all too unlikely. It would be a fantastic plot twist, but eh. Very doubtful.

Leaving us with 2:
McAllister
Haffner

I don't think there is any other way it is not either one of these two. I choose Haffner, but its up to you guys :)

OK a new obvious clue that we should all say, "why didn't we pick up this clue sooner."

 post this reluctantly. Trust me, I am so sure Bertram is not RJ (RJ would never plan ahead to have fake passports since he wouldnt beleive hed ever need to escape or be caught), butt.... A clue in ep 7 when Lisbon and Jane here that Bertram's aunt has a place at "Citrus Heights" 

Sadly this ties in well with the early (I believe it was a reading Jane did on RJ) comments about living with a family member with a citrus tree in the yard... to eerie to no be a clue..
Weird..

Don't kill the messenger. I still do not believe Bertam is RJ..no way

Point of interest. When Lisbon finds SMith in the house, he is on the floor in one room, but Jane and Bertram are in an adjacent room. How is it those two are in different room than Smith. Also, the area where Hafner and Stiles should be...no Hafner or Stiles. Also, when the big blast happens that blows Lisbon off her feet, there are no shadows in any windows of the house where she is approaching..all interesting...