- Reliable hardware support. Especially on laptops - as far as I know it's still basically impossible to get battery life as good in Linux as in Windows/Mac.
- Sane software distribution method that actually works reliably.
- All settings accessible via the GUI. The terminal is still the default for most things. For example google how to disable SELinux (something most users should probably do). You have to edit
/etc/selinux/config
which is really quite complicated for "normal" users.
I think those are the main things. I think it would also help if KDE were the "default" desktop environment instead of Gnome. It's much better, with one caveat - they seem incapable of good visual design! Don't get me wrong, it's a lot better than when KDE 5 first came out, but there are still very obvious spacing issues, and Gnome never has those.