Dude I am not sure how you can rate them on head bangingness, its really hard because from what I have seen they all do it a lot. I saw a video of a concert they did, and they all were doing some crazy ass cool shit. I guess its because I haven't been listening to metal that long, but I head bang for like 5 seconds and I am about to fall over lol.
But if I were to vote it would be fore Johan Söderberg, Ted, and Olavi. Only because when they start doing that head swing thing they do it with some steady chin wang krate teacher stillness or something lol; that to me seems undoable lol.