Although Mashburn is not on the list, he's a better fit than any of those on the list,

In an unrelated vein, I think it would be cool to have Red John turn out to be Stiles's son. This would explain why Visualize protects rj, how rj has access to so many wounded souls who he then turns into killers, where rj learned mind control, and rj's source of unlimited funds. If this turns out to be true, then Brett partridge is my number one suspect (family name.....Brett???) because he would be the right age to be Stiles's son.