This thread should've been XIII, X, and XII because all 3 of them seem to be really relevant to eachother's place in the series.

I would step in for XII and say it had a ton more strategy than XIII. It essentially had the paradigm system, there's archetypes to build, but there's a level beyond that where you script their entire protocol. It may have been more about building an awesome party than utilizing different strengths in different combinations, but I felt for a game where you can just sit back and watch your characters fight, it had arguably more strategy than any FF game before it.