Recommend me a metal band?

[Iota]

Tool are so metal yeah...

System of a Down is awesome I agree, but they are a bit more spontanious than Judas Priest

Who the hell compares SOAD to Priest. I mean, seriously. lol...

So, I'll list some audiolicious bands for you guys. I'll leave out the usual Heavy Metal suspects such as Maiden/Priest/Sabbath because the hoi polloi knows them anyway.

Black Metal:
Krallice
Agalloch
Wolves in the Throne room
Carpathian Forest
Of course the classics such as Gorgoroth, Burzum, Mayhem or Dissection (with the latter one being in fact a combination of Black and Death Metal. Don't listen to Dissection's last album Reinkaos...)

Death Metal:
Cannibal Corpse (Brutal Death Metal)
Nile (Brutal Death Metal)
Bloodbath
Necrophobic (typical scandinavian Death Metal)
Entombed (also Death n Roll)
Classics again: Morbid Angel, Death, Possessed ...

Thrash Metal:
Sepultura (only Max Cavalera era)
Fear Factory (a bit Industrial/Groove/Death Metal)
Soulfly
Classics: Slayer, Exodus (Metallica and Megadeth suck donkey balls)...

Doom Metal:
Ahab (Nautic Funeral Doom)
Sunn O))) (Drone Doom)
Boris (Stoner/Drone Doom)
Earth (Drone Doom)
Ascend (Drone Doom)
Classics: Paradise Lost (Death Doom)...

Stay away from Power Metal, Metalcore/Nu Metal, Symphonic Metal bands like Nightwish or other ridiculously pop-punkish wannabe-metal-shit.

Grindcore's a pretty cool genre too. It's a combination of Death Metal, Thrash Metal, Hardcore/Crust, Noise ...
In case this has aroused your interest I'll list some good bands of this genre as well.