Through a loophole, I present to you THE best biplane fighter of World War Two.
Below: The Hurricane had its
origins in the Hawker Fury
biplane. One Hurricane was
given a jettisonable top wing
to extend its range for
delivery flights.
*EDIT*~I forgot, source is my copy of FIGHTER THE WORLD'S FINEST COMBAT AIRCRAFT - 1914 TO THE PRESENT DAY, by Jim Winchester; a Parragon Publishing Book.
I would have to say the Polikarpov I-153 is the best biplane fighter. During WW2 Goering actually made an order to Luftwaffe Pilots to stay away as the Germans were losing too many aircraft to this biplane fighter. In Russia it was very fast and powerful. I am surprised you are considering the Gladiator and the CR-42 which didn't really last that long. In mainline service the Gladiator was gone by WW2, and the Italians really didn't have too much better than the CR-42 to replace it with.