Queensrych, Testament, Metallica (original not the lame new stuff), Megadeth, Pantera. I know I am forgetting a ton.
More "modern" metal I have been enjoying is Breaking Benjamin, Three Days Grace, Disturbed.
I actually still enjoy 2 christian metal groups Disciple and Thousand Foot Krutch.
I recently picked up an album from a band I had never heard before called Halestorm. They have a really sassy female lead singer and their songs are pretty cool. I'm not quite tired of it yet which is a good sign for a new (to me) group.
If a nation expects to be ignorant and free, in a state of civilization, it expects what never was and never will be. --Thomas Jefferson