Fave: Scorching Back. If only there's a remix of it with vocals.... but I think the lyrics will suck.
Other than that, all the bossfight tracks are neat. They tend to boil your blood up!
On the other hand, Last Battle really sounds like a last bossfight song, (except that it's not really when used for the Undead Core fight). The one during the fight(I think is charge, oh where's my Orgview) with Doctor's 2nd form describes how easy that boss is
(again)
Eyes of Flame is teh real boiler! Gravity(I think) is a Balrog bossfight theme and other than that, I like like like but not as much as the bossfight tracks.
But I think all the tracks suit the stages they're appointed to real well.
btw
here is mentioned three tracks which I probably have or haven't heard before. Unknown 1, 2 and XXXX?
Anyone knows what they are? (one of them should be White, if I'm not wrong)