For something with decent QoS and an excellent mix of "simple to use" and "powerful options", it would be hard not to recommend any ASUS router that can run Merlin firmware.

Merlin is exactly the original ASUS factory firmware (which began life as "Tomato" years and years ago..), with more security/bug fixes and a few extra features tossed in. The GUI is simple, clear, easy, yet powerful.

I run it here, though I have never bothered with QoS on the 300/20 cable internet connection.

If you want a really good router cheap, the TM-AC1900 (T-Mobile Personal Cellspot) routers are actually real ASUS RT-AC68U routers that T-mobile has changed the firmware on. With some hacking (which may not appeal to you), these can have the original ASUS firmware restored to them, and then Merlin easily installed after that. All for less than USD$50 (eBay).

Otherwise, pretty much any recent model ASUS router will work, and with Merlin it will work even better.