For a sailing boat: I consider 2 x 330 Ah LiFePO4 smart batteries. This type, however can not be placed on their sides. For a boat with plenty of heeling and rolling, should I better go for 3 x 200 Ah, instead. The 200 Ah batteries can be placed on their sides and might be more robust for heeling. Other parameters, such as the difference between 660Ah and 600Ah overall capacity, or difference in max current between both alternatives, or space considerations are rather unimportant to me.