I went with Octavarium, but i dont feel like anything sounds forced.. maybe the intro is a little lengthy but hey its called 'progressive' metal for a reason, right? I think it builds up to the climactic ending without any flaws.
Breaking All Illusions imo is the perfect combonation of my favorite two epics ACOS and 8vm, it has parts that are somewhat riff driven like ACOS, but still has so much feeling especially with the guitar solo and ending.
Octavarium is my favorite DT song, but I feel like BAI has the potential to be a top 10 song as well.