I deliberately left the OEM firmware on my Archer C7 because OpenWRT cuts the WiFi performance by ~40%: https://wiki.openwrt.org/toh/tp-link/tl-wdr7500
In the end mucking with open source firmware, while interesting, just wasn’t worth it. I found the ubiquiti solution stable and the UniFi management software (especially their iOS app) are excellent for my needs. Plus mounting my AP in the ceiling means I can cover the entire house from one AP and at the same time keep the rest of my networking equipment stored away in the basement.
I'm personally using a TP-Link Archer C2600 that was on sale for $70 from Newegg in January.
[1] https://wikidevi.com/wiki/MediaTek_MT7621