Go with OpenWrt
instead. It's the original (and far superior) firmware.
If you don't care about 802.11ac and 802.11n is good enough then devices using the ath9k driver are the best supported. The ath9k driver is completely open source without even closed firmware required. This has allowed it to be optimised and it is the focus of projects like Make-Wifi-Fast
. The TP-Link WDR3600 is a dual-band router that uses ath9k for its radios and can be picked up cheaply (i bought two off eBay in the last couple of weeks. £14 and £18 respectively, including shipping).
802.11ac was a step back because every single driver now requires a closed firmware binary blob in order to work. These firmwares handle most of the wifi functionality and so there's very little that can be done to optimise or improve things. The most promising 802.11ac routers are using MediaTek SOCs/Wifi. The closed-source firmware is very minimal and most of the functionality can be done in an open-source driver, MT76. The MT76 driver is in its early days though and no where near as mature as the ath9k driver.
If you want an 802.11ac router and don't mind jumping through hoops
to unlock and install OpenWrt then the "Xiaomi Mi Wifi Router 3G" can be picked up new for under £40. These use MediaTek chips and support both software and hardware flow offloading under OpenWrt 18.06 which increases LAN->WAN performance to almost gigabit speeds (i measured 912Mbps using iperf). Be aware though that while i had no problems with the 5GHz wifi the 2.4GHz isn't yet well supported (no ability to change transmit power levels and it locks the router up after a while. Disabling the 2.4GHz radio resolves the problem).
Unless you have a compelling need for 802.11ac it's probably best to stick with an ath9k-compatible device.
Edited by rhetherington (Sun 29-Jul-18 21:10:51)