Do people hate on Awake? Pretty amazing album and the only DT I like to listen to. There are some guitar (and keyboard) sounds during "Voices" and "Mirror" that absolutely dominate.
I think my favorite metal sound may be on Isis - Panopticon, where they got that monolithic wall of sound, yet its still delicate enough to hear the notes and depth of the chords.
One not-quite-metal album I was admiring the other day is Smashing Pumpkins - Machina, the album is just an exhibition of great guitar sounds and interesting production.