The list of recommendations I give to everyone who asks is - in alphabetical order - here:
Aeon, Agalloch, Alcest, Altar of Plagues, Amesoeurs, Anathema, Atheist, Ayreon, Cormorant, Cult of Luna (Somewhere Along the Highway specifically), Cynic, Dark Moor, Demilich, Diablo Swing Orchestra, Diabolical Masquerade, Disillusion, Eluveitie, Exivious, A Forest of Stars, Gordian Knot, Gorguts, Haken, Incantation, Kamelot, Le Grand Guignol, Mindflowers, Mirrorthrone, Moonsorrow, Nokturnal Mortum, Oblomov, Opeth, Orphaned Land, Pain of Salvation, Pelican, Pin-Up Went Down, Porcupine Tree, Portal (the one with Swarth, not either of the others), Shadow Gallery, Sigh, Silent Stream of Godless elegy, Solefald, Sunn O))), Symphony X, Therion, Thy Catafalque, Tiamat, Tristania, Ulver (just Bergtatt is metaltastic, but all of their albums are worth a listen), Unexpect, Vindensang, Wintersun, Xystus
Those are my favorites and the only ones I really consistently listen to, though I have listen to/know quite a few others