While I don't own the soundtrack to FFXII, I DO own the soundtrack to Vagrant Story, so I imagine the particular answer would be the same since the same composer is responsible.

I don't listen to any one disc the most-I listen to the most sinister and/or interesting tracks in the entire collection and burn a CD of THAT music. Most of FFXII's music is background music that fits the scenes very alarmingly well. I'm not honestly sure if it all stands up to being good music to listen to purely on its own, however. Again, using Vagrant Story as a reference, VS's soundtrack didn't measure up purely as listening music. But in the game... *eyes take on a distant look as I stare off at horrors only I can see complimented by a sinister score of music...*