So in X-2 you had this awesome string of unique boss songs for the final few bosses in the game.

BUT WHICH WAS THE BEST?

Vegnagun Tail & Legs

Vegnagun's Core

Final Vegnagun Fight

Shuyin

Personally:
Their Resting Place
Clash
Ruin
.
.
.
Crash

I think the stupid theater in X-2 lied to me. It said Shuyin's final boss music was named "Demise" or something if I'm remembering right. Either way I thought it was a rather great theme song and I always dragged out the fight with him to hear more of it.