I liked the MKR SNES game. Not hard, but I dare you to point me to one RPG that has super tough battles(don't really(there has to be some, but the point is I can breeze through just about any RPG I have played(hardest likely beating PE and all it's quests)).

There was also Tenchi SRPG that was pretty fun. Though very easy... and not as exciting as the MKR SNES game, imo.