SNES/Virtual Console version is obviously great.
PS1 version has AWWWWWFUL load times every time you go to the menu, but the extras are cool (including anime cutscenes).
DS version has the PS1 cutscenes without the awful load times, and adds some extra stuff, but has the drawback (or benefit?) of being on a portable and not on a TV.
EDIT: The DS version also has a new translation (like FFVI on the GBA) that has been met with some disdain from long time fans but is supposedly more accurate.
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Thank you, Eddie Guerrero.
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