Yes, it was your post I responded to.
The advantage of the RT-AC66U_B1 is that it is more widely available and possibly cost less than the Best Buy only RT-AC1900P. For all WiFi related workloads, they would be effectively the same, except for VPN use. To get effectively the same performance, at least pay less.
The tri-core, 'AX' based, RT-AX58U is not only a 2020 model that is RMerlin supported but on sale, it may even rival the price of the models above (depends on the region you're in, of course).
Even with no AX clients, the latest routers work better than the old AC class routers with more range and throughput in my experience.
'More current', is relative.
Don't forget, that the first post is from 2016.
With 3 cores @ 1.5GHz and 512MB of ram and 256MB of flash storage, the RT-AX58U is a better bet.
https://en.wikipedia.org/wiki/List_of_Asus_routers#ASUS_Wireless_ac_Routers