Mainstream-wise, out of the ones I played...

1. Final Fantasy XII International Zodiac Job System
2. Final Fantasy X = Final Fantasy VIII
3. Final Fantasy XII
4. Final Fantasy XIII (incomplete, had to play on my friend's since I don't have a PS3...)
5. Final Fantasy VI
6. Final Fantasy VII

Spin-offs/other titles

1. Dissidia Final Fantasy
2. Final Fantasy X-2
3. Final Fantasy XII: Revenant Wings
4. Final Fantasy Tactics A2: Grimoire of the Rift
5. Crisis Core -Final Fantasy VII- = Final Fantasy Tactics: The War of the Lions

Not a large range of games...but oh well.