For a same propeller solidity, what are the tradeoffs between blade activity factor and blade number?
One way look at it is your engine is power and prop is load.  The amount of thrust you get will depend on the efficiency of the propeller x engine power output.
So, if one is going for the best fuel economy, the two blade is most efficient, but if you want the more thrust from a larger engine, you either increase the number of blades or increase the chord of the blades.
Both approaches reduce efficiency but increase thrust output, resulting in increased performance.
More high aspect blades, as in a helicopter, will be more efficient at lower airspeeds, but will suffer structural issues (bending) as forward airspeed increases.
Fewer low aspect blades offer a much higher forward speed range but will create a lot more blade interference turbulence at lower airspeeds.  These are commonly seen on turboprop freighters such as the C-130.
It is extremely important to evaluate the design speed envelope of the aircraft when choosing, as forward airspeed reduces interference turbulence.
I took the liberty of adding the A6 Intruder jet aircraft to your list, and found the expected improvement in higher airspeed performance, but a take off run almost 5 times that of the A2D-1 Skyshark.
Enough said there.  Contra rotating coaxial props, and keeping prop speeds below supersonic, also help improve efficiency.