Before to install openwrt I have check the web ui.
There are many thing that other brand do not include, I think mikrotik propose professionnel feature at residential price (mpls, bold, radius, captive portal ect...) The cli is pretty good.
yes its proprietary comes with advantages and disadvantages (few), and feature-wise its very broad, usability is very good if you know how to use it. i agree its subjective by what you want to accomplish with it, but purchasing mikrotik device for openwrt is silly. coming from me who used both and also hate ubiquity's fancy limited software, i would never change routeros to even pfsense.
you are right it didn't even support wave2 up until now with v7 beta. it doesn't support 802.11k/v/r too (and cake qos although current pcq qos works great and im doing it dynamically with my script even better), but it will soon support in v7 both cake and other wifi features and when it does it will be rock-solid single click, not like writing many line scripts to achieve it as i did for openwrt.
edit: also try using winbox, you'll love it. there's "dude" as well for large deployment.