Mine would have to be the Summer Slaughter Tour this summer. Tons of great Death metal bands: Kataklysm, Vader, Black Dahlia Murder, Despised Icon. Just all around awesome.
The best one ever I think was when Jimi Hendrix played the National Anthem weeks before he died. I wasn't there but I saw some old footage. The best I've seen Was when Disciple played in Snyder TX.
I saw Iron maiden 1 month ago and they were awesome!I have been to metaltown,wich is a awesome festival here in sweden with bands like:In flames,Amon Amarth,Dimmu borgir,Nightwish,Danko jones,Dark Tranquillity,Killswith engage,Soilwork,Sabaton,Satyricon and many more.So it was great.