--U.S Aircraft Carriers are the best of the 4 nations.
--German Battleships are the most powerfull of all 4 nations.
--Japan Destroyers are the most well armored of all 4 nations.
--United Kingdom hulls are the most well balanced of the 4 Nations
The key stats of each base hull are-
Weight limit- The max loading of the hull once all equipment and armour has been attached, the closer you come to the max limit the slower the ship will be to the point where even adding engines may not increase the speed.
Weight- The weight of the hull itself with no added equipment, this can be a significant portion of the weight limit and shoudnt be ignored when choosing the right hull for the job, if the natural weight of the hull takes too much out of the weight limit then a different hull may be better for the job.
Defence- The hulls 'natural' defensive rating before any armour has been applied, this usually increases with hull size but not always meaning that the bigger ship may not always be the stronger. While leaving for a mission with no armour at all is very risky some hulls have a high natural defence which can allow the player to get away with carrying slightly less armour then would be ideal.
Turn rate- The ships manoeuvrability rating, essentially how tight that ship can turn, the faster the ship travels reduces this rating but it usually isnt that important.
Aircraft- The maximum amount of aircraft that hull can carry once suitable launch equipment has been added, while a much more important stat for the carriers, warship launched planes can be a useful distraction at times and shouldnt be taken too lightly.
The game also includes a number of special hulls which dont always fit in the mostly linear progression of the standard units giving the player a much wider array of options when choosing a ship to build.