I tried to comment this on YouTube, but it keeps deleting my comments so I have to post here:
As a (Fedora) linux user I would say pick RHEL and Fedora (or Manjaro or PopOS)
My personal choice is Fedora, but I see a plenty of reasons using PopOS or Manjaro. EDIT: after writing this "comment" I watched the rest of the wan show, and I trust Anthony at picking the best distros for them.
I really would like you to try Red Hat or SUSE technical support, since I haven't heard anyone trying them. It would be extremely interesting to hear some comments. Also an average user does not have Anthony at home so this support as a service will replace him partially. I picked RHEL, because it is more widely known, but SUSE is great distro too with a support team available.
Fedora is great choice, because it has really fresh packages and you can get the latest features of for example KVM there. There is huge community behind it, similar to Ubuntu, you can find solutions to almost any problems on their forums. Another reason to use Fedora is the Gnome, it is extremely close to stock Gnome (think it like clean android with no manufacturer customization which you would find in PopOS and Ubuntu). Fedora is also the choise of the Linux founder: Linus Torvalds as well as seemingly many LTT community Linux users. Fedora is one of the most polished and easy to use distro which actually has plenty of user customizability (in my opinion). @Conan Kudo mentioned plenty of other reasons, some of which I haven't tried.
PopOS is great option because it is Ubuntu based and to my knowledge it has quite new packages, not as fresh as Fedora but still. And System76 customizes Gnome quite heavily which is useful, but I do not like.
I do not have personal experience with Manjaro, but I expect ithas some greatness from Arch and also the risk of bricking things easily. Sure it would be the closest comparison to the Steam Deck.
I would not recommend Arch or Gentoo, because you have to figure so many things out before using them, and your experience would not be standardized like most new linux users have. You can customize other distros extremely well too, but it will be more interesting to see you using some distro which an average ex windows user would choose. The ability to pick and buid your distro is great but it isn’t useful to the viewers whose experience would be extremely different and again, an average person doesn't have Anthony helping them at home to fix their problems.
I would not pick Mint, yes it is fine distro, but it is based on Ubuntu, so no difference with other Ubuntu based distros and Mint has the oldschool Gnome. I do not see a reason to learn using that, because Gnome 41 is awesome I am just really subjective. Use Mint if you have specific reason to do so.
I would not pick Ubuntu either, because it is pushing Snap packages and Flatpak is used on almost every other distro. You can install Snaps on almost any distro, but the distro defaults do matter.