I don't want to think too hard right now, but here are some albums I'd put in my list for sure.
Sleep's Holy Mountain
The Sound of Perseverance by Death
Symbolic by Death
Aenima by Tool
The Divine Wings of Tragedy by Symphony X
Rust in Peace by Megadeth
4/26 Circle Takes The Square/Loma Prieta/leer.
5/02 Rin Tin Tiger
6/06 Meshuggah/BTBAM (?)