These should stand the test of time: Metallica (Ride the Lighning, Master of Potheads & And Justice for All), Megadeth (Rust in Peace, Countdown & Youthanasia), Pantera (Cowboys from Hell & Vulgar Display), Testament (New Order, Souls of Black & Ritual). I'm sure if I looked at all my CDs I could come up with some more, but I wanted to do it off the top of my head to see what stood out (always a good test for me).