Looking at 2006, and there was some great metal that came out, including (heads up: long list)
-Ruins of Beverast-Rain Upon the Impure
-Insomnium-Above the Weeping World
-Katatonia-The Great Cold Distance
-Agalloch-Ashes Against the Grain
-Mastodon-Blood Mountain
-Drudkh-Blood in our Wells
-Melvins-(A) Senile Animal
-Drawn and Quarted-Hail Infernal Darkness
-Warning-Watching From a Distance
-Pagan Altar-Magical and Mystical
-Cult of Luna-Somewhere Along the Highway
-Celtic Frost-Monotheist
-Summoning-Oath Bound
-Cannibal Corpse-Kill
-Negura Bunget-Om
-Enslaved-Ruun
-Wolves in the Throne Room-Diadem of 12 Stars
-Solitude Aeturnus-Alone
-Deftones-Saturday Night Wrist
-Kayo Dot-Dowsing Aneome With Copper Tongue
-Gaza-I Don't Care Where I Go When I Die
-Ahab-Call of the Wretched Sea
-Isis-In the Absence of Truth
-Melechesh-Emissaries
-Last Days of Humanity-Putrefaction in Progress
-Amorphis-Eclipse
-Sunn0))) and Boris-Altar
-Converge-No Heroes
-Negative Plane-Et in saecula saeculorum
-Om-Conference of Birds
-Gorod-Leading Vision
-Death Breath-Stinking Up the Night
This year in particular is important to me because
1.) this was the year I really started to get into metal, and I haven't been the same since
2.) Several of these albums are what I consider either the band's best (Ruins, Insomnium, Melvins, Agalloch, Warning, Negura Bunget and a several more) among their best (Wolves, Celtic Frost, Drudkh, Cult of Luna, Cannibal Corpse and Pagan Altar) or just underrated (Deftones, Isis, Converge and Death Breath) Hell, I'm probably forgetting something so anyone else knows help me out. All I know is that it's hard for me to pick a favorite
Long post short: 2006 is a one of the most important years for me from a music perspective.