"Brutal"? Define something more clearly. :/ You want fast, unbalanced, non-dynamic music? -> you need to listen to Hate Eternal...the ultimate level of unrelenting-ness.
If you mean the bands who are consciously TRYING to be as brutal as they can?
You will either find the stupidest Death Metal bands around or you need to listen to Grindcore. I think the latter is the better choice for good "brutal" music. Death Metal should not, IMO, be focused primarily on brutality. That's like high school posturing. So just go for Hardcore and Grind/Brit-core which are a more sincere and unfiltered expression of uncontrolled (teenage) rage.
Go for early Napalm Death (Scum and From Enslavement to Obliteration) or Blood (start with O Agios Pethane, then go backwards), hell, go for Black Flag and Siege!
If you just want favorite Death Metal bands that sound tough as opposed to 'interesting'/'different', I'd have to say Sinister (Cross the Styx) and mid-period Vader (Litany).
If 'mega fast' is not in your requirement of 'brutalness', you might want to try (newer) Heresiarch's Hammer of Intrasigence.
Cryptopsy (first two albums) sounds like an obvious recommendation for all "brutalness seakers". Do avoid all their imitators, better study classics than waste time on copy-cats.