FFI:
In the Origins remake the Citadel music is phenominal.

FFII:
Rebels hideout theme like crazy

FFIII:
Tell me the truth (I think that is the name) it's played when you are in Unne's cave and a couple of other places.

Also the music on the boat with what's her face after you kinda 'expand your horrizons' and see the whole world.

FF IV: The Zeromus battle is pretty awesome.