My favourites are...:

Eyes on Me - FFVIII
The Successor - FFVIII
Julia - FFVIII
Libera Fatali - FFVIII

One Winged Angel -FFVII
Crazy Motorcyle - FFVII
Red XIII's Theme - FFVII
Aeris Theme - FFVII
The Planet's Crisis - FFVII

Melodies of Life - FFIX
Song of Memory - FFIX
Black Mage Village - FFIX
Unforgettable Sorrow - FFIX

Zanarkand - FFX
Prelude - FFX
Hymn of the Fayth - FFX
Yuna's Theme - FFX
Ending Theme - FFX
Via Purifaco - FFX

There is more.. but these are the top.