Difficult question indeed ....
I think, in contrast to the britains, who built the first batches of their
Hurricanes and Spitfires still with two bladed props, the french seems to
have favoured three bladed ones for the fighters of that era, just before
the war. But a contra prop may be quite a different affair ! Probably three
blades would allow a lower diameter, compared to two blades and so allow
the installation of guns further inward. But that's just an amateurs opinion,
we need the experts here !
At least, three blades (or better six of two three bladed props) look better !