The heaviest (nonPriest) concert that I attended was 1994 (Metallica/Suicidal Tendencies and Fight) at Star Lake Amphitheatre outside Pittsburgh, Pa. .
I've seen Metallica 10 times and that was by far their best performance. Also last hurrah for Suicidal Tendencies. Too bad because they were so kick ass.
Fight was a last minute replacement for Candlebox (maybe there is a God). They opened the show with a killer performance. Overall, major badass concert.