Check out the following albums:
Black Sabbath - Paranoid
Black Sabbath - Sabotage
Iron Maiden - Number of the Beast
Iron Maiden - Powerslave
Metallica - Ride the Lightning
Metallica - Master of Puppets
See if you notice any distinction in music quality (riffing, solos, drumming, song structure, lyrics, etc) between those 3 bands and SOAD, FFDP and Disturbed. If you enjoy the albums and want to get further into the Metal genre as a whole from there, just drop me a mention.
I haven't checked out The Ocean yet, but I can confirm that Neurosis is that piff. Start off with Through Silver In Blood, if it doesn't click during the first listen just give it one more try and you'll be
.
After you "get" that album, check out the rest of their stuff (specifically Enemy of the Sun, Times of Grace, and A Sun That Never Sets).
Also, check these albums out if you've never listened to them:
Cult of Luna - Somewhere Along the Highway
Agalloch - Ashes Against the Grain
Boris - Feedbacker
Katatonia - The Great Cold Distance (Brave Murder Day is their best album, but this release is probably a better introduction based off of what you already listen to)