I installed Manjaro to two of my friends that I’d say are mid-level and they’ve been using it without problems for years. Even if it’s arch-based, it comes with everything it needs to be easy to use (most importantly a graphical package manager) and because it’s arch-based it never lags behind with software updates and you got the AUR if you need it. Manjaro is to Arch what Ubuntu is to Debian basically. Yes, they have fucked up a few times in the past, most notably the certificate fiascos, but none of that affects its usability for a beginner, at worst they won’t be able to update for a few days while they renew the expired certificates.

Edit: and I recommend you use Plasma, it will feel very familiar if they come from Windows