With Simon leaving, I'd like to nominate John Waters for the job. He has a book coming out, and I'm sure he'd take the job even if he didn't need the plugs.
Simon will be a tough act to follow, with his particular talent for being simultaneously loved and hated. John Waters is a good fit.
(Note on the last show: nice of them to bring Casey back to add some charisma to the stage. The two finalists live in a charisma free universe.)