Okay I voted for 8, and let me tell you why.
I loved ff7... but I never really got attached to the characters. It was more of a yay its done kind of thing. So the scene with red and his family just didn't do much for me.
I played ff9.... I really didn't like the game at all.
I loved ff10, but I felt that the ending wasn't really an ending, but more of a bridge between ff10 and ff10-2
Now ff8 had a complete ending. It left you tense, in suspense, and wondering.... then it completed the entire story. And it didn't leave you wondering, after the credits it COMPLETED the story. As in when they said the end, they meant it lol! And I was attached to the characters, I cared what happened to them.