The definitive version: Final Fantasy 4: The Complete Collection (PSP) FF4 has a TON of different versions, and no two are exactly alike. Sure the characters have zero personality and the plot is all over the place, but it's fun learning (and exploiting) the quirks of this game, such as which jobs are horribly overpowered, and which are completely useless. But if you did, you would find that FF3 holds up surprisingly well. And I have no idea how you might acquire a copy, so I won't even speculate. What about the rest? Well, the only other version of Final Fantasy 3 is the original, released on the Famicom in 1990 and available exclusively in Japan. This remake is available on DS, PSN (for PSP and Vita), Steam, and more, making it widely accessible. The basics remain intact - plot, dungeons, bone-crushing difficulty - along with some minor tweaks that help smooth out some of the original's rough edges, such as making more character classes viable during the endgame. The original game has been completely rebuilt using vibrant 3D graphics along with a freshly remixed soundtrack. Thankfully, it's also an excellent remake.
The definitive version: Final Fantasy 3 (DS/PSP/PC/Mobile) As this is the only official English version of the game available in the West, it's the winner by default.