IIRC, Merlin is built from the Asus firmware, so Merlin is very stable and somewhat more featureful and secure than Asus vanilla. I have been happy with it for years, having moved off of openwrt and ddwrt.

Merlin does not aim to accomplish the same as something like openwrt, which is a larger project and lends itself to more involved customization and etc.

When it was just me, I could tinker but we were working from home and now we have kids with internet use also.

Basically, I use Merlin because I want more features but i cannot really tinker with it; the WiFi is our production environment. I considered having an internal lab network but it just wasnt worth the overhead.