Dungeons and Dragons: Warriors of the Eternal Sun
the boss, Burrower, slowly drove the whole valley mad.
Can't explain the Beastmen, or the Azcans, though.
and Shining in the Darkness is one of the few good Dungeon Crawlers for a 16 bit system, mostly due to smooth walking, and a easy to learn interface (arrows and A/c to confirm, B cancels). Good walls and pounding music help, too.
But, the best Genesis RPG? probably one I've never played, but I'm open to suggestions. and Shining Force is more Strategy than most RPGs.