I believe it is Bertram, because the only thing, in my opinion, that would remove him from the list of Patrick is the "fact" that Bertram is not good at poker. But he might as well pretend not to know how to play to fool everyone. So I think it's him. If Red John is as good as Patrick Jane, he must obviously be good at poker, but Red John, like any good sociopath, could hide it.
