Mikrotik is a lot more configurable, and easy to tune. Its also have a lot more features.
I had some ubnt devices for a test. IP adress to a vlan was scripted, and all was ok. untill upgrading software. Couse of the script (removing bridge, adding bridge) the ubnt device, stop responding at ethernet. (no link) I had to drive to about 20 customer, push the reset button, and configure without the script. After this no more ubnt.
I still miss, autochannel in mikrotik. That must be the only feature better in ubnt.
It (was) also to low l2mtu at interfaces, so MPLS was not possible.
ubnt as radio card, is another story. norting is more rock solid than XR2 and SR5. (maybe new groove 2.4,still in test)