I've discovered so many bands this year that I can't pick a favorite so I'll just list them:
Ahab, Altar of Plagues, Caravan, The Cinematic Orchestra, Cocteau Twins, Deerhunter, Do Make Say Think, Dragonland, Falloch, Fen, The Flower Kings, Gifts from Enola, Iron and Wine, Jesu, The Knife, Lights Out Asia, Maybeshewill, Mew, The Moody Blues, My Dying Bride, Myrath, The National, Nest, Nick Drake, October Falls, Pendulum, Popol Vuh, Red Fang, Scale the Summit, Shape of Despair, Slowdive, Steve Hackett, Stratovarius, Uneven Structure, Vildhjarta, Voyager, While Heaven Wept, Wolves in the Throne Room, Woods of Ypres, 3
I've also been on a metal binge recently so here are some great bands I've discovered just this week:
Elvenking, Dark Moor, Keep of Kalessin, Satyricon, Chthonic, November's Doom, Decapitated, Septic Flesh, Carach Angren, Graveworm, Origin