This is perfect.
YouTube - One-Winged Angel (Sephiroth Theme Metal Version) with lyrics
This is not perfect.
YouTube - One-Winged Angel [Final Fantasy VII ACC Long Version]
I wish I knew how you make a "long version" of a song that is already over 6 minutes...
Why do you have to mess with success, Square?
Though honestly, the worst is probably Crisis Core
YouTube - Final Fantasy 7 Crisis Core One Winged Angel Theme