I love FFT but FFVI is better. I don't see how anyone can miss the greatness that is FFVI.
FFT is awesome but FFVI does more for me. I remember having to save up to buy it and just playing it non stop that year. I still beat it often enough to keep everything fresh in my mind and it holds up to the test of time.
It is hard to compare the two since they are so different. FFVI was pretty revolutionary for us Americans. It was pure gold. FFT was basically a rip off of TO (although better). The story was awesome and more flowing than FFVI but it didn't have the innovative spark or creative style that FFVI did. Characters bland?? hmmm... the dialogue in FFVI is awesome and each character has distinct personalities. It was a bigger cast than we were used to and everyone could find a character to call his favorite.
The best thing about FFVI, Kefka. The most insane and maniacal evil villain to ever grace a FF game. They both have weak bosses in terms of difficulty but FFT had a really poor last battle.