Ne Obliviscaris - Citadel
Honorable Mentions:
Soen - Tellurian
At The Gates - At War With Reality
Godflesh - A World Lit Only By Fire
Agalloch - The Serpent & The Sphere
Pallbearer - Foundations of Burden
Not really close. I didn't think this was a particularly good year in music, at least as far as metal and hard rock is concerned. Citadel blew everything else out of the water. A tremendous sophomore effort that nearly equals some of the best work in the genre (Opeth, namely).
Speaking of Opeth, holy god was Pale Communion terrible. Like, really terrible.