Presuming 1939 levels of readiness and tonnage, which would have been the strongest Navy? Presuming a strictly maritime confrontations, no Fleet-in-Beeing policy, no Homefleets, and a neutral theatre of war. (For example, RN could confront USN in either the Atlantic or Pacific but not in the Baltic or the Med., IJN vs RN would be in the Pacific or Indian Ocean, but not the Atlantic, and so on). Think World of Warships with actual Navies.