I think this one will end up pretty close actually.
2 Steve Ritchie classics there!!
While Firepower gets overshadowed by Black Knight, I actually think it is the more challenging machine. Great sounds, challenging multiball, and fast, fast, FAST game play if it is set up correctly.
While I own a Black Knight (and have owned 4 others) I honestly would have to go with Firepower here. Don't get me wrong, I LOVE Black Knight, but the challenge of the multi-ball on Firepower gives it the edge. That and the background music does not annoy me as much on Firepower.
I really don't think you would go wrong with either choice honestly.
Chris