Fantastic concept and execution. If I had to choose a faction based just on the music, I'd go with the shamans.
I liked the way the two pathway diverge in style and then partially come back together for a showdown in the Destruction section, e.g. with the vocals in the Royalty Destruction track. At least, that's how I interpreted it. It was very well done.
Reminds me of certain RTS and other strategy games where by default you play as one faction and then get to play as the faction that was previously your enemy. But that might just be because I went straight for the Youtube link, and there was only one of those so I didn't really exercise my right to choose which to listen to first!