DragonBall Z: It's the story of the saiyan Goku who is extremly strong and searches for strong guys to fight all over the universe.
One Piece: It's the story of Luffy who dreams of beacoming the lord of the piratesbfinding the legendary treasure, the One Piece. He travels island by island to find a crew to help him find this treasure.
Naruto: It's the story of a ninja called Naruto who wants to become strong and become the cheif of his village: the Hokage.
Hunter X Hunter: It's the story of Gon who becomes Hunter and is on a trip to find his father who is one of the strongest Hunters of all time.