What I mean by "classic DT" I mean "what I enjoy the most."
I don't really care for 4 songs from Octavarium (The Answer Lies Within, These Walls, I Walk Beside You, and Never Enough, the rest is great), and I don't really dig anything from Systematic Chaos, other than ITPOE and Repentance. I thought Black Clouds sounded like a solid prog metal record, especially after two albums I thought were largely inconsistent. I know everyone disagrees, but I think BC&SL has some of their best material.
Don't get me wrong, TOT is awesome. But I never much cared for Honor Thy Father, Vacant, and I've always thought In The Name of God was a little bit too long. The only song I dislike on BC&SL is Wither.