The "Merlin firmware" for Asus routers like the RT-AC68U supports codel/fq_codel under QoS. The routers have solid, more than adequate hardware, 802.11ac WiFi, and many features. The custom "Merlin" firmware is based on the stock firmware with added features, making it even better supported than dd-wrt/openwrt currently imho.
Most wireless routers have 4-port switch (gigabit in newer models), so you can use them as a wired router, and even add another switch if need be. I don't see the need for a second modem, a solid wireless router would be the way to go imho.