Took me 12 hours to beat the GBA ver minus the grinding so 15 hours average. I explored too xD
^ GBA version also includes the additional post game dungeon that NES and PSX versions lacked.
If you do a speed run - that would be less than 10 hours :O
I would have said " final fantasy games that i played " xD
I take 2 or 3 more time to finish the game than most people :P