As title your choice for best fleet cruiser in the early 1930s, put this end in the 1932
I suppose that the Washington type was the best for the mission i list last classes available by countries
Exeter or Norfolk for full size
Suffren or Dupleix see this is not a true class
after this there was the 7.5" gunned 25 de Mayo of the ARA
for those that like the 6 inch cruiser the alone modern 6 inchers were
the Duguay Trouin class
Di Giussano class
Koenigsberg class & Leipzig
Principe Alfonso/Libertad class
8”: On paper, the UK ships don’t look so good, but they held up well in the war, able to handle all missions at least adequately.
The American cruisers look good on paper, but were not optimized for the type of combat they saw: close range, anti-ship, night.
The Atagos were optimized for exactly that fight. Also had a useful search capability.
Zara: again, powerful on paper, not so much when tested in combat.
None of those early 6” cruisers were very impressive.