Worstgen

examples :
• F-22 Raptor ( from USA )
• or T-50 Pak Fa ( from Russia )

if not Aircraft Fighters , Balistic Missiles also wouldn't dissapoint , examples :
• Shaheen 3 ( from Pakistan , range 2750 KM )
• R-36 ICBM ( from Russia , range 10.000 to 16.000 KM )
i feel like if SSG is creating something like this , it wouldn't be as powerful as R-36 though . ICBMs ( Intercontinental Ballistic Missiles ) like R-36 are capable of destroying cities
the Marines don't need something as powerful as that anyway

Submarines that are more powerful than Law's sub also would be incredible .
especially since most of One Piece planet is water , and Submarines are stealthy ( they are hidden deep underwater , also doesn't generate loud sound like Aircraft Fighters )

• like Kilo class Submarine ( from Russia )
• another example , Astute class Submarine from England

i feel like Tanks , like Leopard 2A5s ( from Germany )
and New Pacifistas , like from Movie Z
are not going to be that good . they will have to be carried by Marine Battleships , so they won't be able to reach the targeted locations ( i mean , other lands separated by seas ) independently . and most of One Piece Planet is water

it is better to have weapons that can reach any targeted locations independently , like Aircraft Fighters , Ballistic Missiles , or Submarines ( though they might be more expensive than Tanks , and New Pacifistas )

Modern Battleships ( Battleships that are made entirely from steel , like Sigma class Corvette below , from Netherlands )
are going to be good , though i feel like current Marine Battleships are still really capable of doing battle in seas' surfaces

besides i want something that's completely new , not another Battleships .