At a risk of sounding obvious, the best way to have an access point is to have an access point. Modern access points have very specific hardware that is specific to them and is rarely encountered on routers, not to mention general-purpose devices.
I recently published here a guide to installing OpenWrt on Sophos AP 55/55C/100/100C. In the aftermath of writing that guide, I have a few of those APs with OpenWrt already installed lying around, so if you are in North America, send me a private message, I'll make you a deal... 