Well if I was going to be a bit more semi-serious, I would probably make the list like this:

Antiquity
Final Fantasy
Final Fantasy II
Final Fantasy III

Golden Age
Final Fantasy IV
Final Fantasy V
Final Fantasy VI
Final Fantasy VII
Final Fantasy VIII
Final Fantasy IX
Final Fantasy: The Spirits Within ~ The Fall of Square

The Dork Age
Final Fantasy X
Final Fantasy X-2 ~ The Beginning of the End
Final Fantasy XI
Compilation of VII ~ The Apocalypse ~ Beginning Signs of the Dark Age
Final Fantasy XII

The Dark Age
Fabula Novis Crystallis
Final Fantasy XIV