[psynapse]

Amen. Death's Human and Cynic's Focus are on my favourites list. I will add:

Opeth - Blackwater Park.

Slayer - Seasons (1990).

Megadeth - Rust in Peace (1990).

Fates Warning - A Pleasant Shade of Gray.

Spiral Architect - A Sceptic's Universe.

Dream Theater - Awake.

Emperor - Nightside and Anthems.

Soilwork - Chainheart Machine.

Morbid Angel - Domination.

Dissection - Storm of the Light's Bane.

Gorguts - Obscura and From Wisdom...

There is always nostalgia for the ground broken in the 80's, but the 90's yielded many great bands' best.

[kochthesecond]

I would also pull in

Ulver - Bergtatt

In Flames - The Jester Race

Meshuggah - Destroy Erase Improve

The 90s hold so many good and interesting directions for metal!

[psynapse]

Destroy Erase Improve is indeed killer. I also love Amorphis' Tales From the Thousand Lakes.

[groovy2shoes]

I would also pull in:

Dark Tranquility - The Gallery

At the Gates - Slaughter of the Soul

Edge of Sanity - Crimson