I'm gonna get flamed to hell and back for this, but I actually never liked X3's soundtrack as a whole. I like Blizzard Buffalo, Gravity Beetle, and Blast Hornet, the rest are extremely generic muffled rock blaring repetitively out of the speakers. Strangely enough, that crappy style of music was never really explored again in the series, and to me it stands out pretty badly like a sore thumb.
The X2 soundtrack, by contrast, is EXTREMELY fucking good and it's a damn shame no one ever remembers it. It's so good. SO GOOD. >:O
The X1 soundtrack is great too, but I actually owned that game as a kid and heard the songs so much I just take them for granted.