For me it's PeppermintOS.
I started my Linux adventure a few years ago, and haven't owned a Windows PC since.
I currently use Arch on my main rig, and I wanted to install Linux on two old laptops that I found laying around in my house
I then remembered the first distro I ever used, which is PeppermintOS, and I was amazed at the latest updates they released.
They even have a mini ISO now to do a net-install with no bloat, with a Debian or Devuan base.
Sadly, I believe the founder passed away a few years ago, which is why I was really happy to see the continuation of this amazing project.
Bazzite, a gaming-oriented immutable distro with up to date Fedora packages and kernel, a lot of the kernel patches you'd want for gaming, automatic daily updates in the background, the option of installing the Nix package manager and Distrobox out of the box. They even have a Steam Deck version that works just like stock UI/UX wise but with all the added goodies.
Plus, on rpm-ostree/ublue-os as a whole, it just amazes me to no end you can basically look at deploying a distro as if it's a git repo these days. Wanna try Gnome? Rebase to the corresponding image and reboot, your data is still there. Don't like it? Quickly rollback or just pick the previous entry on GRUB. Incredible stuff, I'm sticking with those if I can help it for the foreseeable future.
+1 here. I wanted to write the same. Silverblue/ uBlue in particular has a huge potential.
It already is extremely user friendly, but if someone could develop an even more "noob"-friendly version with a great welcome-starter that shows you how to install stuff, a good looking KDE rice, and sells it as extra-distro with it's own website and iso, then it could easily replace Mint as the #1 best beginner distro!
Heck, Bazzite is most of the way there. With how quickly it's been improving, wouldn't surprise me if it had all that pretty soon.