The US has produced classics in just about every genre of metal and is also among the best in almost every genre as well, arguably with the exception of black metal. That's not to say that the US is not without its good black metal bands, even if some are of too weak of fiber to handle it: Absu, Alioth, Averse Sefira, Black Goat, Cult of Daath, Dark Psychosis, Demoncy, Grand Belial's Key, Havohej, I Shalt Become, In Memorium, Into the Sunless Meridian, (arguably) Inquisition), Judas Iscariot, Krieg, Krohm, Masochist, N.M.E., Night Conquers Day, Nightbringer, Profanatica, Resuscitator, Tearstained, Von, Von Goat, Weakling, Weltmacht, and Wind of the Black Mountains have all put out worthwhile material, not including Akhenaten's side projects that took place while he was in Germany, foremost among them being Flagellator. Some of these Black Twilight Circle bands even are not too bad. I have a Furdidurke tape and an Ashdautus CD that I certainly don't mind at all, as well as the related Bone Awl, and I'm sure I would find more to like the more I listened.
Sometimes it's absolutely absurd how moronically overlooked the US is when it comes to death metal. It's like the only bands anyone knows are Death, Suffocation, Immolation, Incantation, Morbid Angel, Obituary, Autopsy, and maybe Deicide and Atheist. As if those bands alone were not enough to rank them among the best along with Sweden, Finland, the UK, and the Netherlands. People don't even think about shit like Master, Nocturnus, Order from Chaos, Hellwitch, Divine Eve, the aforementioned Brutality, Monstrosity, Malevolent Creation, Morpheus Descends, and dozens more. Honestly, the US, taking into consideration both quantity and quality of good material (and ignoring worthless elements like population size and the amount of shit bands, as if they were relevant), is probably the 'best' country for death metal, for whatever that is worth and whatever that actually means.