1. Iron Maiden, soon to be 17 times.
2. Black Sabbath with all four original members once and with Dio and Vinny 3 times.
3. The Metal Masters tour with Judas Priest, Heaven and Hell, Motorhead, and Testament. Seriously, I don't know that a better line-up is possible.
4. Slayer / Megadeth / Anthrax was another one of those near perfect lineups.
5. Nothing too impressive but I'm glad to have seen a lot of bands a good number of times, Motorhead 4 times, Mastodon 4 times, Alice Cooper 7 times, Megadeth 8 times, Testament 4 times, Rush, AiC, and Kiss 3 times, etc.
12/16 - Queens of the Stone Age