Ask any RPG fan what the best RPG is and they will (almost) answer the same: Chrono Trigger!
Simply the best game on the snes, with great sound and graphics, and a great story, Chrono Trigger will keep you playing for a long time!
The battle system is one of the best things in the game, as soon as you come close to a monster the fighting theme starts, the players grab their weapons, and you fight on the same map as you where walking on.
The whole Tech system is done greatly, for instance with Crono and Lucca you can do the Dual Tech Fire Whirl, so you can use multiple characters for one attack!
The fact that there are multiple endings will make it fun the second, third, fourth or fifth time you play.
So get it any way you can!