Post-metal generally isn't that great, but banRAB like Agalloch and Opeth frequently abandon lyrical work for compositional efforts. Bear in mind that I am by no means a metalhead. I recommend:
Opeth - Morningrise
Black Sabbath - Paranoid
Agalloch - The Mantle
Meshuggah - obZen
Iron Maiden - Nuraber of the Beast
Slayer - Reign in Blood
Takes care of progressive, black, death, power and thrash metal.
Ok, I got one more, very little known but awesome Australian band from way back in the 90's... the were called Alchemist (NOT the hip hop artist but the same name, nothing like it)... I dunno if they're still together not but damn, they were GOOD!
My list is mostly the same as ShallowAbyss, with a few exceptions.
1. The Black Dahlia Murder
2. Larab of God
3. Five Finger Death Punch
4. Iron Maiden
5. Avenged Sevenfold
6. Pantera
7. Austrian Death Machine
8. KoЯn
9. Megadeth
10. Protest the Hero
August burns red
bring me the horizon
as blood runs black
misery signals
as i lay dying
norma jean
parkway drive
the devil wears prada
between the buried and me
unearth
Like AC/DC they`re often classified as a metal band. Largely for their huge impact on the genre. Firstly, being part of the NWOBHM which really put metal on the map. Secondly, they were highly influential on the speed and thrash metal movements.