@itsfoss I really want tp say Arch, because I do love Arch and what it can do. But I also understand that having a user-first distro is... Not the best starting point. It's not exactly unstable in my experience, but assuming we don't ger derivatives like Endeavour and Garuda, it'd be a hard sell for anyone to get into.
I'm a firm believer of the "There are only 5-7 distros and everything else is a flavor of one of yhem" school of thought, so it'd probably go to Debian or some derivation of it. Something relatively easy to get into, but still allows you to customize it and get it running how you want.