Had to return to OpenWrt, can't withstand unreliable WiFi from ROS and is too much time consuming to fine tune it. OpenWrt WiFi just works fast and reliable out of the box without having to tinker with it.
offtopic: I had Linksys WRT1200 and WRT3200 running for several years with OpenWrt. Wifi sucked soooo much - it was a pain. Even with its 4 external antennas I had so bad wifi coverage AND shitty throughput.
Switched to Chateau then. Did not expect anything from a device without external antennas and - from the datasheet - inferior wifi specs. But turned out: Mikrotik Wifi is a no-brainer for me. Coverage is sufficient and just works. No more wifi tinkering.
I have 3 Cap AC on Openwrt now. So I have experience with both Router OS and OpenWRT.
Maybe in your use case you have enough coverage so that 1 access point is enough, and the band you use is always the same (always 2 ghz or always 5 ghz).
But my observations were:
- OpenWRT is clearly faster in pure throughput (1 wifi device doing an iperf3 test to a wired device). But going from 200mbps (RouterOS) to 400-500 mbps (OpenWRT) maybe does not matter for you. It doesn't really for me either since I mostly use Internet which is 100 mbps anyway.
- OpenWRT does roaming a lot better. First of all switching to/from 2 ghz and 5 ghz on the same access point works seamlessly. With RouterOS, I had to configure the 2ghz band to have 7db less than the 5ghz band for my devices to connect to the 5ghz band when reallt close to the access point. Then I was loosing range on the 2 ghz. Also when a device would connect to one band, it would be stuck on it for a very long time. For example, the device connects to the 5 ghz, I move, it stays on the 5ghz even if the 2ghz is clearly stronger. It takes a really bad 5 ghz signal or a very long time for the deviec to switch.
- Across all access points, OpenWRT does roaming. I can start an iperf3 test to a remote wired computer and move across all 3 access point seemlessly, switching from one access point to another or on one band to another very quickly without loosing the connection. And it does it pretty fast.
- OpenWRT configuration is faster out of the box, with RouterOS I had to define the non-overlapping channels, define the power of the 5ghz band, read a lot and tweak a lot of things, watch Mikrotik conferences on best practices, etc. I am glad I did, learned a lot, but in my use case at home, OpenWRT was clearly simpler.
So depending on the needs both can do the job, but when digging further I find OpenWRT better for me. Also super stable without one reboot since flashing and configuring.
My 2 cents