The Final Fantasy I dungeons were fun enough at first, but they soon grow boring. Or at least that's how I found them, especially when you consider the length of them and the fact that there's four of them. On the other hand, I did quite enjoy the Lunar Ruins. Still yet to actually do Dragon's Den (though I've got a save just outside it waiting for me), so I'll have to check that out (and play FFVA too) before I can give a definitive answer.