Xiaomi - Mi Router 4A Gigabit Edition

Was using Xiaomi AC1200 for half year. It's decent with rare stutters if you keep bitrate at reasonable value Then tried TP-Link Archer AXE75, even so it's recommended by Virtual desktop, it worked like garbage for me, so I returned it after week of use(maybe I had some defective unit) And now I switched to PRISMXR Puppis S1, its cheep and work great

I want to upgrade my Xiaomi Mi Router 4A Gigabit Edition router and am looking for a good Wi-Fi 6(E) router with OpenWrt support. What options would you suggest as the best value for the buck or best overall? I don't need USB ports and just 2 LAN ports are enough for me so pretty much any router would fit (I don't mind having more features but they are secondary). But I want the best Wi-Fi performance and reliability for an average apartment. Also, it would be nice if the router is compact and can fit in a standard network equipment box.

I am using Mi Router 4 and Mi WR30U myself. Both are cheap but the WR30U has worse documentation for being less popular.  If you are only looking for a small upgrade without going extra, Mi Router 4 (not 4a) has 128MB flash, mainline OpenWRT support and decent documentation. It can be found for a little as ~$7USD second hand so it will fit in your budget even if you spend all of it importing 

I have 4 APs myself: two Zyxel NBG6716's, a Xiaomi Redmi AC2100 and Xiaomi Mi Router 4A Gigabit Edition. All of them are running OpenWrt, not the manufacturer's original firmware. That said, I wouldn't necessarily recommend any of them. Neither Xiaomi is good with original firmware and the Zyxels are getting a little long in the tooth.