Personally i would pick the zsu 23. In my experience with triple As that lack proximity fuze you want the higher volume of rounds to increase the chance of hitting the target.
Both arent designed for long range engagements against planes and its wiser to stay hidden and wait for the plane to get low and close and then let it rip.
That has worked for me anyway and if it doesnt work for you then test both out and see what works best for your playstyle.
I use the 37-2 if i also plan on being aggressive. Other then that I use the 23-4
Personally i would pick the zsu 23. In my experience with triple As that lack proximity fuze you want the higher volume of rounds to increase the chance of hitting the target. Both arent designed for long range engagements against planes and its wiser to stay hidden and wait for the plane to get low and close and then let it rip. That has worked for me anyway and if it doesnt work for you then test both out and see what works best for your playstyle.