Distro watch's ranking isn't a good metric since it could be gamed easily. My understanding is it's just based on the number of clicks on the website, which I bet is gamed. I doubt MX Linux is actually that popular. I've never known a linux user who runs it, I have ran it myself several times. But I have known more Void users than MX users.

Addition: This isn't a dig at MX. I enjoyed the times I've installed it. I personally like it, although it's not my main go to distribution. Just that distrowatch's ranking isn't reflective of reality.

This has information to how they do it https://distrowatch.com/dwres.php?resource=popularity

I installed MX Linux years ago and have not looked back. It has been incredibly stable and easy to upgrade. While I had ubuntu and mint regularly get trashes on system updates in the past.