FF 7 - it's just great
FF 9 - same
FF 10 - Spehre grid is fun
FF TA - jobs and tactics
FF 10-2 - jobs (again)
FF 5 - jobs (i like jobs )
FF 1 - old good classic
FF 2 - interesting level system
FF 4 - nothing to say
FF 8 - junctions...
FF 6 - curse those random encounters and Kefka

Crystals,Tactics,FF 11 and 3 i haven't played (yet )