I think Debian is the best Linux distribution because of its simplicity and stability. It's extremely lightweight out of the box without bloat. Package availability is massive. It's extremely stable, albeit at the expense of older package versions. However, this means that it "just works". It never breaks on me. I'm not having to do regular system maintenance nor troubleshoot broken upgrades. Everything works all the time. This is especially important when deployed on servers. I also prefer the apt package manager. There are just tons of reasons to use Debian. There's good reason that so many other distributions are based on Debian.

If someone didn't want to use Debian then I would recommend openSUSE Tumbleweed.