Mice and men - just got a weedeater CD which I listened to tonight - 16 tons.
Very recently into eyehategod (seeing them in a couple of weeks), buzz-o-ven and sourvein. Don't mind some 13 but the vox are often a bit BM for my liking (not a BM fan at all).
Like you I like heavy and I find slower shit is often heavier - I don't care for metal cliches like high sounding endless fast guitar solos that mean little musically to me and some metal vox (mostly BM, especially second wave and after) make me think of gollum with throat cancer. Some of the early shit is good though - sabbath, venom, bathory etc.
I'm more of a punk guy so the crossover with some genres of hardcore punk is where my metal preference lies - grind, crust, sludge. Less wank, more grit. Actually I'm more of a post punk and industrial/post industrial guy than any of this but sometimes you need to burst a head vein with some heavy guitar and bass.
Also a huge Melvins fan.