I have only played VII,IX, X and currently playing VI, but I think FFX has a fair bit of replay value.
For example, customising different weapons, changing people's direction around the sphere grid. Then there is maxing out your strength and health, trying to defeat all the monster arena bosses, defeating dark aeons (in PAL version).

So maybe I wouldn't replay the whole story a lot, but for just turning it on and having a save near the end where you can work on defeating dark aeons, etc, I think it has replay value in that sense.