Awake, Six Degrees, Train Of Thought are my personal favorites, each one for different reasons.
Awake is the darkest, great guitar sound, amazing bass tone, everything has space to breathe and still sound heavy.
Six Degrees is amazing since it sounds heavy but balanced, i love that every instrument has it's own space even though it is a little compressed.
Train Of Thought is definitely the heaviest DT sounding album,i love the way the guitar is crunchy but clear, and bass is still audible matching perfectly with the guitar tone.