I know it's kind of a silly quest, but if you had to chose ONE track (try not to make a list!) that is the most challenging you have ever heard, what would it be? And I'm not asking for the greatest melody or whatever (could be melodic of course), just something that could literally be almost an overdose if it could be eaten.. Full-on-blasting-trance-which-is-psychedelic! Can be 120 BPM, or 160, melodic or not, you name it.. But of course it has to have something (almost) no other track has.
I'd say, at this moment: Reflecta - Creatures. I don't play it that much, because I tend to not listen to tracks I really know well, but when applied = maximum dammage.
http://www.youtube.com/watch?v=u-6Ga1CLsMY
Shoot!