Brett Partridge likes to call Jane on his decisions to many Red John cases, and is present at quite a number. He works at the CBI so he has at least a close connection to Jane and Lisbon and the team. In the video he fights Jane on the what's clever and what isn't, and Brett likes to fight Jane's decision on things.
His name is Brett which is a similar (allbeit differently spelt) name to Bret Styles, who one can guess is Red John's father. Bret Styles and Jane get on too well for it to be him, but there's a strong connection between Styles and Red John. Similarly, this is the case with Bertram. I've no doubt that every single person on Jane's suspect list is either a FRIEND OF or Disciple of Red John, but alas only one of them is actually Red John...
Bob Kirkland has taken a vested interest in Jane's investigation, which suggests friend or disciple of Red John but I doubt Red John himself would care as much as that.
Ray Haffner, again, probably knows of Red John through Visualize, but doesn't actually have to skills to do anything. Jane plays him effectively in that one episode, and his reveal as Red John would be boring... Although he does ask Cho if he thinks Jane is smarter than him, but that's such a weak link...
Reede Smith is a boring nobody, and I think his reveal as Red John would be even crapper than Ray. At the end of the day, he's just an FBI agent who clashed with CBI when jurisdiction came up, not exactly fun.
Thomas McAllister, is a creepy perv, but that doesn't mean he's Red John. I mean, he was in one episode, and all he did was try to rape Van Pelt. If he WAS Red John, he'd have known VP was CBI and wouldn't have tried anything. RJ has been watching Jane for a long time, he's not going to get fooled by that cheap trick. Plus if his obsession with outsmarting Jane was so strong, he'd like to do it a lot more.
So my conclusion is Brett Partridge as he's the only real character Jane legitimately doesn't get on with, and is - as Jane will tell you - a ghoul. Plus, he has a freaky voice, which kinda sounds Red John-y from the season 4 finale.
Although chances are it's none of them :) I hope we find out who, but don't catch him... They can't catch Red John, they finish the show.
