1) I like the FF's with flexible job systems: V and X-2. Tactics has the ultimate extension of that. Especially nice is the mixing and matching of primary and secondary skills sets.

2) Breedable monsters.

3) You can get most enemies to switch to your side.

4) A complex, almost labyrinthine plot.

5) Wide range of specialized characters with neat abilities.

6) A large number of subquests and propositions keep you immersed and challenged.

7) Music is nice.