I know this post is a can of worms. There are so many variables in play client types, radio support, applications in use, density of access points the list goes on and on.
Discounting all the various factors for a moment. Assume you have a 11ac access point that supports 2x2:2.
OFF THE TOP OF YOUR HEAD ...
Voice/Data Client Mix -- How many clients per radio ? How many clients total per AP?
Data Client -- How many clients come to mind per radio ? How many clients total per AP?
Just trying to take a simple pulse what comes to peoples minds. Sure we can talk all the math but looking for a quick anwser that comes to your mind.