What best games are in Nintendo DS

Well, that depends on what sort of gamer you are.
If you like music, maybe Elite Beat Agents.
If you like action, maybe Naruto Shippuden: Ninja Council 4,
If you like cosmetics, maybe Imagine: Makeup Artist,
Ect, Ect.
Basically, rent the game before you buy it, to see if you like it, because different people like different games.