I've never completed the final areas of II, III, IV, and VI, but this is the order that I played them in, anyway, I think:

  • FFVIII
  • FFX
  • FFX-2
  • FFIV
  • FFI
  • FFII
  • FFIII
  • FFIX
  • FFVI
  • FFXII
  • FFVII
  • FFV