For me it's a tie between two people. There are only two people on the list that somehow fit Rosalind's description of RJ, that would be Ray Haffner and Brett Partridge. Unlike most people on this site, I believe Partridge is in fact dead. However, I believe all 7 have a connection to RJ in some way. My other pick would be Gale Bertram, I know in the season premiere his lines were obvious but hear me out, nobody else in the entire show refers to Jane as "Boy Wonder" which was his circus name. I realize he does not at all fit the description but I do believe he has a deeper connection to RJ than we suspect. Haffner at this point looks like the best suspect simply because of his high tech background and his description, but like many suspects that we have met in the show, he seems a bit "too good to be true" at this point. And allow me to address an ongoing theory on the site, if Partridge did fake his own death somehow, and there was no body to show for whenever they find Lisbon, don't you think Jane would automatically believe that Partridge is the #1 guy, to me that would be exactly what the real red john wants, so whenever they do not find a body, Jane is going to suspect that Partridge is not dead.