Jinchu 1 or Land of Lightning Treasure. Unless you already have a strong team.

Kage Treasure and GNW are the better choice (but only in the very long run....) with the above mentioned, you get 2 decent teams. I would recommend you get Jinchu 1, then do 10 draws in GNW treasure (gurantees Fuguki) and you have a nice water main team (get Sailor Sakura to make it complete).