Generally speaking I agree about X-2 not having that great of a soundtrack. It could also be because the game was supposed to be more lighthearted compared to FFX.

FFX on the other hand has an amazing soundtrack, things like No Hope No Dreams, This is Your Story, Someday the Dream Will End, Run, and when you battle Seymour inside Sin are some of the best pieces I've ever heard in FF. The music fits the atmosphere and the events perfectly.