Final Fantasy VII
Final Fantasy Tactics
Partly Final Fantasy VIII
Final Fantasy IX
Completely Final Fantasy VIII
Final Fantasy X
Final Fantasy VI
Final Fantasy IV
Final Fantasy V
Final Fantasy
Final Fantasy II
Final Fantasy Tactics Advance
Final Fantasy X-2
Final Fantasy VII Dirge of Cerberus
Final Fantasy XII
Final Fantasy III
Final Fantasy XII Revenant Wings
Final Fantasy VII Crisis Core
Final Fantasy Dissidia

I can't really say, when I've played the rest, but at least I can remember the years when I've played the Final Fantasys here on top.