I like most posted here.
I tend to like the old school amps boosted or modded:
- old in flames, machine head, carcass 90’s tones all 5150
- fear factory demanufacture: jcm 800 Jose mod?
- nevermore - this godless endeavor Mesa rackto
- a lot of Adam D productions (killswitch engage, unearth, parkway drive) peavey 5150 blended with a Framus cobra/dragon
- for HM-2 sounds I like Harms Way as they have perfected that tone imho: mix of HM-2 and clarity
- Earth Crisis - Gomorrah season ends: I think Mesa 2:90 with a triaxis
- most if not all Decapitated albums: mix of different amps but so agressive and direct sounding often a bogner uberschall, Mesa and Randall blended but also 2 x EVH 5150
Honorable mention:
- He is Legend: Adam T has such a great 5150 or Mesa dual rec sound and his riffs are awesome

not extreme music but pretty heavy and grooving riffs