I've had very impressive success running upstream OpenWRT on TP-Link hardware: I have Archer C7 access points running with literally years of uptime.
That being said, for any new application, I suggest using at least an 802.11ax AP, because cheap 2.4GHz devices that support 802.11ax are becoming common and using an 802.11ac router means that your 2.4GHz devices will be stuck with 802.11n, which is quite a bit less efficient. Even if you don't need any appreciable speed, it's preferable to use a more efficient protocol that uses less airtime.
Ditto, the TP-Link's Archer A7 firmware is a security nightmare [1] but with DD-WRT installed it is very stable and reliable.
[1] Daughter invited ~10 classmates to prepare for a science competition, and one of them had a virus (I assume) that hacked TP-Link's firmware to draft it into a botnet. WAN connection would drop every hour for a few minutes, plus unexplained internet traffic while nobody was using it. Resetting firmware did not help, installing DD-WRT fixed it once and for all.
I think I actually retired an Archer C7 for this. The goal was something 2.5G ready because the city has systematically rolled out fibre to every neghbourhood around here and I'm just waiting for the knock.
Honestly if you're not invested in maybe Ruckus or Aruba, I don't think there's much better than OpenWRT on a decently supported AP. I had a bunch of the C7s with OpenWRT and they've been totally bulletproof. I only upgraded to R650s recently and it's not clear beyond maybe the antenna setup and the fact that it's ax now that it's much better.
That being said, for any new application, I suggest using at least an 802.11ax AP, because cheap 2.4GHz devices that support 802.11ax are becoming common and using an 802.11ac router means that your 2.4GHz devices will be stuck with 802.11n, which is quite a bit less efficient. Even if you don't need any appreciable speed, it's preferable to use a more efficient protocol that uses less airtime.