wow, I always thought 7 would easily be the most popular, especially the 3rd movt.
I find it rather easy to interpret (not that i've studied it) - 1st movt: torture/war (hell breaks loose in the development - the shrieks of pain, the barbaric repetition of the second subject. 2nd movt: I don't find to be a nice piece, I see it as a dream, covering the harsh reality. 3rd movt: the relentless ostinato reminds me of how everyone had to be kept in check and no one could step out of line (unless they wanted to go to Syria) and the second subject is someone trying to break free with the continous rhythm attacking it from all sides.
just my ideas.