I would not recommend the PlayStation version. It's got load times for menu screens and is generally pretty gross.
If you own a Wii, it's $8 on Virtual Console, which is a perfect emulation of the game (It's listed under its original numbering, Final Fantasy III). There was a GBA port of it in 2007 that was pretty good, and even had a new translation and an extra dungeon.
It's becoming obnoxiously hard to find though. That was the most recent time that I played the game. But honestly, I prefer the older translation by Ted Woolsey. It injects a little personality to things. Also, the small screen diminishes the game for me, and the sound and music are noticeably compressed on the GBA cart, so it doesn't sound
exactly like it should.
Any day now I expect Square to announce a 3DS remake of the game,
akin to what they did with FFIII and FFIV on the DS. But there's never been an official word on that, and it's been years since even the last rumor of such a project. There's also a chance that the 3DS virtual console will start selling SNES games, but that could be quite a ways away.