I'm going with ActRaiser. I've never played it, but have always heard good things.
I didn't really care for Bonk's Adventure. Bonk's Revenge is supposed to be better, so I would probably still play it, but I'm not that ecstatic. I don't really find Comix Zone or StarTropics all that much fun. Super Mario RPG is a great game, but just a bit more interested in ActRaiser.