Of course, no one could ever fully replace "our oracle for over 50 years" (Ray Franz quoting Karl Klein or someone else on the GB back in the days of GB I in CofC somewhere ), but I have to wonder just who on GB II has come to fill Fred Franz's shoes the most. It seems like it is David Splane. He appears to be in charge of the Writing Department, proposes and pushes thru the GB most of the doctrinal changes (he announces them so they're his baby), and like FF, fancies himself musically inclined. I've read here that various ones have said he was more studious than the average big shot elder when forum members knew him. That is isn't saying much, of course, in the Witness world, and I doubt he was the college dropout with some formal Greek under his belt that FF was.
In several ways he doesn't seem as bright at FF was. At least Splane doesn't think out the consequences of his doctrinal changes like FF did—not that FF wasn't also short-sighted, but he seemed at least somewhat better in this area. FF seemed more reluctant to change a doctrinal issue unless he could offer a replacement. Splane seems more eager to reject certain long-established doctrine/belief without offering much to replace the spurned interpretation. For example, there's the nebulous dismissal of type/anti-type, shadow-reality interpretations, which had a long respectable place in earliest Christianity.
Input here?