In my opinion is Ray haffner WHY??

just look when Lisbon in that dream or called what you want, Bertram and Smith called here LISBON, and Ray is the only one who called here TERESA.

Now go back to 6x01 Red john to Jane on the phone : Sorry patrick TERESA can't....

i also believe that the seven suspects are all connected somehow, there is a lot of possibilities
 and bruno is playing with our minds as he said in an interview about 6x01 that red john could be Lisbon or patrick jane.

I have to admit, Partridge was my No. 1 suspect. So after he died, I thought to myself, ‘Of course he’s going to go first!’
That’s the thing. Everyone has different No. 1 suspects, which is good. That’s one of those things as a writer; you can spend a lot of time weighing which one people think is the likely suspect. That’s very much a subjective choice. I know that are a lot of people out there who think Jane is Red John still
.…even though you’ve said explicitly he’s not!
I know. They don’t necessarily have to believe me, I suppose. I’ve never denied that it was Lisbon. So I suppose it could be Lisbon.

Twice we have been told that RJ is medium height (just under 6 foot), medium build, not soft but not muscular(around 150-170 pounds)

Bret Stiles - too thin, not tall enough
Gale Bertram - too tall, too "well-built" for RJ
Brett Partridge - ideal height, possibly too thin but could be classed as medium build
Ray Haffner - a little too tall, perfect build
Bob Kirkland - a little short, good build
Tom McAllister - bit tall, good build, perhaps too "well-built"
Reede Smith - too tall, too big

From this we can definitely eliminate Smith and Stiles 

Now age, RJ is middle aged
Partridge is too young, Bertram is too old, as is the Sheriff

Now we are left with Kirkland and Haffner

Kirkland has been shown to us as an obvious choice for RJ, but way too obvious. My bet is Kirkland has his own personal reasons for why he wants RJ dead. The hospital scene where he asked one of RJ's followers if he recognizes him is puzzling and will perhaps be revealed to us later on in the season. Kirkland has a weird voice which is what was described by the little girl at the cemetery , i could definitely see him putting on the RJ voice from the phone calls.

Haffner is the right height and weight for RJ , but i can not see him putting on the weird voice. The visualize part makes me suspect him alot, but this also seems too obvious. Bruno Heller says he knew who RJ was right from the start of season 1, and the only person who has been with the series that long is Partridge. I personally do not think he is RJ as his actor has confirmed Season 6 Episode 1 was his last appearance in the series.

With all the suspects pretty much ruled out, i think Gale Bertram is the strongest candidate. This is 100% reliant on the fact that Heller said he knew who RJ would be right from the start, and a Future Chief of the CBI is the only part i could see being set in stone as a future character.

As none of the clues point to one suspect

1) Heller has lied and he didn't know who RJ would be right from the start
2) The medium build and medium height clue is false, as none of the suspects really fit the description except i guess Kirkland.
3) RJ is not one of the 7 suspects

All of the clues will come together and i think everyone will be surprised when we reach the 8th episode of Season 6 and RJ is revealed, but for now, Heller has purposely made it so none of the clues can point to one character alone. All the clues point away from Stiles and Smith, so i am not sure about that. But my money is that either Haffner or Bertram is RJ.

I forgot to point out in my previous post accusing Haffner, that the "big clue" that "won't become immediately obvious" that Bruno talks about in the scene where RJ grabs Lisbon in the season premiere, IS that he left Lisbon alive. Her being alive is the clue.

At the end when Raymong Haffner was lifting weights, there was something about his face that fits in with RJ so much. His face looks like he is Red John :3

It's Haffner. He is agile, charming, fits the physical description etc but the most important clue is that RJ left Lisbon alive. WHY would he leave her alive? Because he cares about her, as he told her in the hospital. He is Red John and Stiles is his father. Kirkland was either Lorelei's sister's boyfriend and is out for his own revenge, or he is RJ's right hand man.

No idea what that meeting between Bertram, Mcallister and Steele was about though.

#5216 made a good point that they may have overlooked themselves. Red John is a crack shot, as shown in Red Sky in the Morning. 

Surely the best shot would be the person who's had precision training, likely a government agent? 

I agree with that theory that Haffner is RJ, i just felt i'd add this minor info.

I think its ray haffner most because of the discription in the last episode where it said he was a middle aged man, in good physical condition and is good whistler. The whistling part stood out to me the most because when haffner leaves after talking to lisbon the show makes it quite clear haffner is good at whistling and his talk with lisbon displays narcissism which is also a trait that RJ is supposed to have.