8 titles recommended if you like One Piece: Giant Mecha Soldier of Karakuri Castle
One Piece: Baron Omatsuri and the Secret Island
One Piece: Chopper's Kingdom in the Strange Animal Island
One Piece: Curse of the Sacred Sword
One Piece: Dead End Adventure
One Piece: The Movie
One Piece: Stampede
One Piece: The Desert Princess and the Pirates: Adventure in Alabasta
One Piece Film: GOLD