I rather do not make a ranking. It is very hard for me and basically only the first few have the place I gave them here:
Final Fantasy VII Sepher Sephiroth: One-Winged Angel
Final Fantasy VII - One Winged Angel - YouTube
Final Fantasy XIII Ending: Kimi ga iru kara
FINAL FANTASY XIII Sayuri Sugawara - Kimi ga iru kara - Youtube
Final Fantasy Prelude
Final Fantasy Vocals Collection I: Pray - Prelude - YouTube
Final Fantasy VII Sephiroth's Theme: Those Chosen by the Planet
Final Fantasy VII - Those Chosen by the Planet [HQ] - YouTube
Final Fantasy VII On our Way
Final Fantasy VII - Ahead on Our Way [HQ] - YouTube
Final Fantasy IV Theme of Love
Final Fantasy Pray - 05 - Into the Light (Theme of Love) - YouTube
Final Fantasy VI Terra's Theme/Wanderer of Time
Final Fantasy Pray - 04 - Wanderer of Time (Terra's Theme) - YouTube
Final Fantasy VII Aerith's Theme
Final Fantasy 7 Music - Aerith's Theme - YouTube
Final Fantasy Theme: Final Fantasy/Pray
Final Fantasy Pray - 10 - Pray (Final Fantasy) - YouTube
Final Fantasy VII Main Theme/Cloud's Theme
Final Fantasy VII - Main Theme [HQ] - YouTube
Final Fantasy VI Forever Rachel:
Saddest SNES Music: #1 - Forever Rachel - Final Fantasy 6 - YouTube
The Rest ist without rankings:
Final Fantasy VII Crisis Core Main Theme
Final Fantasy VII Crisis Core - Main Theme - YouTube
Final Fantasy VII Crisis Core The Price of Freedom
Final Fantasy Crisis Core The Price of Freedom (Last Battle Extended) - YouTube
Final Fantasy VIII Eyes on Me
Final Fantasy VIII (eyes on me By faye wong) - YouTube
Final Fantasy X Suteki Da Ne
Suteki Da Ne (Rikki) - YouTube
Final Fantasy IX Over the Hill
https://www.youtube.com/watch?v=EGAWcVKDqxg
Final Fantasy IX Kuja leaves Burmecia
https://www.youtube.com/watch?v=QRSzoseug5g
Final Fantasy VII Interrupted by Fireworks
https://www.youtube.com/watch?v=6Pi9xgOXvTs
Final Fantasy X Yuna's Theme
https://www.youtube.com/watch?v=oIw1sdmRyq8
Final Fantasy VII Dirge of Cerberus Longing
https://www.youtube.com/watch?v=JzG24vGN_H0
Final Fantasy IX Dali Village
https://www.youtube.com/watch?v=elKGnfiwR2E
Final Fantasy VII Those who fight/Fighting
https://www.youtube.com/watch?v=3B_EctHjsR4
Final Fantasy VII Those who fight further/Still more Fighting/Fight on!
Final Fantasy VII - Still More Fighting [HQ] - YouTube
Final Fantasy XIII-2 Last Hunter
Final Fantasy 13-2 OST - Disc Two - 03 - Last Hunter - YouTube
Final Fantasy VI The Decisive Battle
Best VGM 358 - Final Fantasy VI - The Decisive Battle (Boss) - YouTube
Final Fantasy IV Battle with the Four Fiends
FF4, Appearance of Golbez's Four Lords of the Elements - YouTube