ALL OF THEM

But really I would have to say disc 3.

-The cool scene with Alexander and Bahamut
-Black Mage Village and Bobby Corwin
-Getting to go to new continents
-Desert Palace was an interesting area that I liked exploring
-Esto Gaza I really liked
-Getting your airship to travel anywhere, including Daguerreo, which was great
-Getting to go to Terra, and watching that great scene where Zidane finally breaks down.