Phantasy Star II.
Silent Zone (Dezoris World Map Theme) is my favorite song out of the whole series! I love "Under", "Phantasy", "Movement", "Excite Town", "Exclamation", and "Prologue" as well. Hell, I just love the entire PSII OST.
I love PSIV's soundtrack though.
The End of The Millenium
The Age of Fables
Laughter
Ooze
Thray (Rune)
Staff Roll
Those are my favorites from PSIV.