How about a festival-style smackdown, three simultaneous stages, sabbath/maiden/priest on each stage, whoever plays the loudest and has the biggest crowd in front of them wins...
It would suck to go to that show cuz I'd wanna see all three. Well, only if Ozzy were singing for Sabbath. And yeah, only if Maiden played music from Powerslave, Piece of Mind, and Number. OK, OK I'd probably be camped in front of the Priest stage, cuz there isn't a single bit of music they've put out I didn't like. Not a one.