I had lots of trouble with my Asus AC-68U as a router but it works great as a WAP, no trouble at all. Have you considered buying a really robust non-wireless router and just using the DSL-AC68U as WAP?
I know how you feel, though, I really like the UI of Asus stuff but my experiences with my AC68U have put me off the brand, I would probably go with something clunky but reliable that can run dd-wrt if I get fed up of the firmware.
Personally I really like have separate modem / WAP / router even thought its a bit messy because you can change / upgrade things individually without throwing out the whole setup just because you want to upgrade to the latest Carlos Fandango wireless standard.
Chunks