I've used OpenWRT, and variants of it, since about 2014. I most recently purchased an ASUS TUF AX6000 and installed OpenWRT on it, to run a wireguard client; I need a fast router for encrypted VPN at 1Gbps.

OpenWRT supports *hundreds* of routers. You get a lot more fine grained control.

For example, you can better customise SQM traffic shaping e.g. Cake/fq_codel. It has nice VLAN features...

I mean. It's Linux. It's the power of Linux. They make running a Linux router easier for mere mortals.