1. Iron Maiden x10 (Specifically happy to have seen the AMOLAD tour)
2. Black Sabbath x4 (3 times with Dio, once with Ozzy)
3. The Metal Masters Tour in 2008 (Priest, Sabbath, Motorhead, Testament)
Those are what I'm most proud of but that doesn't include seeing a ton of great bands sometimes up to 6 times just because it's not all that uncommon for them to tour.
5/4 - Rob Zombie?
5/11 - Ghost
5/13 - Mastodon / Gojira
5/21 - Primus
6/28 - Iron Maiden / Ghost - Bergen, Norway