The best changes to often. And 20 devices to one would be quite bad. WIFI air space is only half duplex and shared (which you would know.)
So my best solution would be to get wired what I can and then depending on the situation (small office, corp office) make choices accordingly as to the brand and support.
The small office can use what you get at office stores. Corp types get the big gear (and bills) from the names.
What is the Best Small buisness Wireless Access Point?
Will have around 20 wireless devices connected to it.