... Everything is really good. I can't choose.
TWEWY: Awesome graphics, gameplay, and storyline.
Castlevania: Not the best graphics, but the gameplay and storyline make up for it.
RODS: A game that has a good story (almost made me cry) and stays faithful to the Comp version with great gameplay.
FF: 2nd Best Story ever (well second to KH) and great gameplay.
One that you should try:
KH 358/2 : Best DS Graphics, best gameplay best story, best sound, best voice acting. Best EVERYTHING!