For OpenWRT - at the moment the current code is at the fork called LEDE - here is a ToH: https://lede-project.org/toh/start - both projects want to reunite but it seems progress is slow - use the 17.01.2 release for LEDE at the moment - it's the most stable current version.
As for the hardware - If you want to use OpenWRT/LEDE you have to be selective about supported WiFi chips. ath9k is battle tested but no ac wifi. ath10k should work reasonable well if you only want to have an access point. Broadcom / Mediatek and others can have issues - stability or signal strength depending on the driver.
If you want something off the shelf - Mikrotik and Ubiquity and to a degree TP-Link and Asus models get good reviews. In terms of hardware and antennas Mikrotik and Ubiquity are usally better.
You probably want 802.11ac and 5GHz - at the moment 802.11ac Wave2 is probably not worth the money because you need support on the client side and that is rare.
TP-Link Archer C50 would be my budget pick (30€) and runs LEDE - no Gigabit through. Archer C7 for Gigabit.
If you don't mind soldering a serial console and flashing LEDE using the bootloader get a used Cisco Meraki MR18 / MR24 without licence and wall mount kit for a few $ from ebay - top notch hardware and antennas (but ath9k not ath10k) and lot's of CPU / memory.
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For OpenWRT - at the moment the current code is at the fork called LEDE - here is a ToH: https://lede-project.org/toh/start - both projects want to reunite but it seems progress is slow - use the 17.01.2 release for LEDE at the moment - it's the most stable current version.
As for the hardware - If you want to use OpenWRT/LEDE you have to be selective about supported WiFi chips. ath9k is battle tested but no ac wifi. ath10k should work reasonable well if you only want to have an access point. Broadcom / Mediatek and others can have issues - stability or signal strength depending on the driver.
Check out kmod-sched-cake and sqm-scripts for the latest in research regarding bufferbloat - https://www.bufferbloat.net/projects/codel/wiki/Cake/ together with airtime fairness - https://linuxplumbersconf.org/2016/ocw/system/presentations/... you can archive some crazy results in good wifi (only on ath9k / mt76 partly on ath10k).
If you want something off the shelf - Mikrotik and Ubiquity and to a degree TP-Link and Asus models get good reviews. In terms of hardware and antennas Mikrotik and Ubiquity are usally better.
You probably want 802.11ac and 5GHz - at the moment 802.11ac Wave2 is probably not worth the money because you need support on the client side and that is rare.
TP-Link Archer C50 would be my budget pick (30€) and runs LEDE - no Gigabit through. Archer C7 for Gigabit.
If you don't mind soldering a serial console and flashing LEDE using the bootloader get a used Cisco Meraki MR18 / MR24 without licence and wall mount kit for a few $ from ebay - top notch hardware and antennas (but ath9k not ath10k) and lot's of CPU / memory.
+1 For LEDE/OpenWRT, I'm running 17.01.02 (uname -a=Linux LEDE 4.4.71 #0) I am using a TP-Link TL-WDR4300 v1 and am very happy with it so far.
I would probably be more happy with ubiquiti unifi