By the power of truth, I, while living, have conquered the universe.
No way I can pick one, there are so many that stand out for me.
Cloaked in Blackness is even better than Under Cover of Night, I would go as far as to say. Still, Moving was also a brilliant track, very well remastered from Ambient Wonder. The Maw's opening just sends shivers up my spine whenever I hear it and picture the Autumn crashed on the mountain of Halo, it looks so beautiful.
Then there's the soundtracks of Halo 2 and ODST, they're simply sublime and the latter definitely shows how versatile the music in Halo can be. I loved the solo saxaphone and light piano notes as I walked through the darkened streets of a crumbling New Mombasa.