When I originally got into metal I pretty much listened to nothing but thrash metal (and NWOBHM, which I could write a whole post about), and a ton of it. Of course that included Metallica, Megadeth, Slayer, and Anthrax, but I also found some really amazing hidden gems like Artillery - By Inheritance, which is a pretty technical thrash album with traditional metal vocals and very very good lyrics. Basically every riff is amazing and memorable.
Another gem that sticks out to me is Vio-lence - Eternal Nightmare which is more raw and hardcore-inspired. The punk vocals might be off-putting at first but listen for the non-stop blood-pumping riffs.
And if you just want pure, raw San Fransisco thrashy goodness, Death Angel - The Ultraviolence is pretty much the epitome. Shout-along choruses and tons of fast, rough, dirty riffs.
Nowadays my metal horizons are much broader but I listen to it a lot less than I used to, just because my horizons are way broader in general. Some absolute favorites that you might not have heard, off the top of my head:
Kvelertak - Self-titled - Fast and dirty fusion of black metal and rock & roll. Kinda like if AC/DC was from Norway in the '90s. Really fun stuff. Also check out their latest album Nattesferd if you like this but wish it was more melodic and more classic rock inspired.
Neurosis - Through Silver In Blood - Weird, raw, atmospheric sludge metal. Somewhat industrial too. I could listen to this for days, it puts me in a really intense trance.
Strapping Young Lad - City - Extremely loud metal, no specific subgenre really describes it but it's kinda like, thrash/death/industrial/rock & roll. Every track here flows into the next beautifully and the intensity only lets up for brief moments, until the brilliant cover of Cop Shoot Cop's "Room 429". It's only 40 minutes long and definitely worth listening to all at once.
Devin Townsend - Terria - The mastermind behind Strapping Young Lad, Devin shows his more thoughtful side on his solo work, and this is probably the best of it, in my opinion. Extremely dynamic prog metal that never gets too pretentious and never takes itself too seriously. Just good sounds and memorable songs.
Mercyful Fate - Melissa - Come on, you gotta listen to Mercyful Fate. Everyone should love Mercyful Fate. The goofy vocals are an art form of their own, and the riffs and solos are completely perfect.
Electric Wizard - Dopethrone Basically Black Sabbath turned up to 11, pulled off so well it's addictive. Dark and oppressive and very heavy, good drugs music.