Which version of Final Fantasy VI? It has been released in North America several times.
The first version was released for the Super NES under the name Final Fantasy III. This contained the original English translation by Ted Woolsey, which is generally regarded as a good (if not completely accurate) translation. This version contained some censorship of language, nudity, and alcohol references as mandated by Nintendo at the time, but the gameplay itself was unchanged.
The second version was released on the original PlayStation. It retained the original name of Final Fantasy VI and was released as part of the Final Fantasy Anthology compilation, which also included Final Fantasy V. This was more or less the same as the SNES version except for the correction of a few translation errors (including the name). Also, full-motion video cut scenes were added, and a few other bonus features (such as a bestiary and artwork gallery) were included.
The third and (so far) final version of the game was Final Fantasy VI Advance, which was released on the Game Boy Advance. This version contains a completely new translation. The new script is a more accurate translation of the Japanese script, but many people prefer the original translation. Most of the censorship from the earlier versions was removed, but the FMV cut scenes were taken out. This version also includes four new Espers, new equipment, a new bonus dungeon, and a new enemy arena. There were also some bug fixes and some other minor changes to accommodate the smaller GBA screen. Personally, this is the version that I would recommend getting, especially since the earlier versions are harder to find now.