You can't go wrong here.  Final Fantasy 6 (released as 3 on the SNES in the US) is hands down the best in the series.  Play through the story of Terra, now with FMV cutscenes.  This is worth playing even if you played the original, just for the FMV sequences.  Then you get Final Fantasy V, long hailed as the best game the US market missed out on.  This is truly a great re-release.