Ecco had insane music.
I love Final Fantasy music as well, Nobuo Uematsu is kind of a genius.
But really theres only 3 games who's soundtracks I actually listen to pretty regularly: Legend Of Zelda - Ocarina of Time(best zelda OST), Sonic The Hedgehog 2 (best sonic OST), and Killer7 (which is probably the best of them all; it's such an underrated work of art).
I'm a video game music nerd. Trying not to explode all over this thread.
Edit: I never played Final Fantasy VI before, but I just started recently. I was totally fucking impressed by this games version of the Prelude theme (which is in just about every FF game in some way or another). I think this might be my favorite version. http://youtube.com/watch?v=q_XS0aNy53U
It's fucking amazing.