The only thing I still don't like much about recommending Linux Mint to beginners is that their Cinnamon desktop still uses Xorg which has some horrible display tearing on some Nvidia graphic cards (can be usually fixed with some tinkering and this is also only my personal experience), which is usually not a thing with Wayland and being Xorg it also means it has inferior touchpad gestures (surely not as smooth as Gnome or KDE) which can be important for notebook users. While being very user friendly it is one of the more resource heavy DE's I would say even more than Gnome or KDE. It also seems to have some problems with battery life? The official Gnome and KDE desktop packages for Linux Mint are pretty outdated, are still Xorg versions and aren't officially supported AFAIK (maybe there are some good community maintained packages). Otherwise I agree it's one of the best choices.

My personal favorite for beginners is Fedora Workstation or KDE edition, because it's up to date and fairly hassle free and stable (except the frequent kernel updates which sometime cause issues, but booting the older kernel is straightforward) and does not much modify its packages from the original or push their products on you like Ubuntu.