Sooo here's how it goes for me
===Eargasm / "Jesus christ these are the best songs ever and I will love them all the way to my grave" tier===
1. Octavarium (tears in my eyes. I cri every tiem)
2. Illumination Theory
3. A Change of Seasons
Honorable mentions: Learning to Live (awesome but not an epic), Metropolis Pt. I (same), Another Hand/The Killing Hand (same), A Change of Seasons 1989-1990 demo (seriously that shit's great)
===Awesome songs/always-fun-to-listen-to tier===
4. Six Degrees of Inner Turbulence
Honorable mentions: Breaking All Illusions (it's about as good as Learning to Live but at this very day I'm a little burned out, it may slip into the higher tier every now and then), Finally Free, Vacant followed by Stream of Consciousness (sounds about as "epic" as any epic DT song in terms of scale and emotional prowess)
===Great epics I rarely listen through tier===
5. In the Presence of Enemies (to listen to this song, I need the same mood I have when I play an adventure/RPG game or watch some adventurous show. It doesn't happen much).
6. The Count of Tuscany (it's pretty good, but I don't really feel it. Sometimes it's fun for the riffs. Happy Holidays 2013 made it much easier to embrace it, though)
Honorable mention: The Ministry of Lost Souls, Sacrificed Sons, and more psuedo-epic songs that require the right mood.