I think in the last season, there have been enough clues for pretty much anyone on Jane's list to be RJ.

The question isn't "who" anymore, the more important question now is "why" and "how". 

Whoever RJ turns out to be, B. Heller better have a good back-story for him.

Personally, I'm rooting for Ray Haffner or Kirkland. But Kirkland is a little too suspicious, with the "do you recognize me? It's very important" scene, so I'm thinking it's a red herring. 

Brett Patridge is just too goofy in my opinion. I know most theories point to him being RJ, but I'd be very disappointed if it was him. I hope the actor can pull off RJ in that case.

And what's the deal with Lisbon's hand injury being mentioned but never explained and not of any significance? Another red herring?