Microsoft: Halo Music, all of it.
Nintendo: Metroid music, some of it ololoolol.
Sony: None, everything sony is bleh to me.
For Microsoft, I would have to go with Halo as well. For all that Halo's campaign has going for it, the music stands out, perhaps, the most. I also enjoyed Danny Elfman's work in Fable, as well as the Chopin in Eternal Sonata, if that counts. And of Nintendo games, I guess I would say I like the music from Zelda the most. Never owned a Sony console.