These are just some highlights off the top of my head.
Koloss by Meshuggah. Still the masters of metal minimalism and/or Bootsy Collins-inspired funk bass. Hits: “Do Not Look Down”, “Marrow”, “Break Those Bones Whose Sinews Gave It Motion”, all the other tracks. Killer live show (with Decapitated and Baroness opening!).
Non-2012 music that I especially loved in 2012:
The out-of-print Japanese import of Living Colour’s Biscuits. So many awesome live tracks.