If you install Maui 17.03 and don't upgrade plasma you will have a pretty much rock solid desktop user experience.
Though KDE Plasma also is available as LTS version and KDE Neon has a LTS ISO for that purpose. This means Plasma will only get minor fixes here and there but no real new features which are almost everytime the root cause of some new bugs.
If you use Maui 17.03 without upgrading plasma (enable the maui-xenial-backports-neon repo) you will basically have the same but without minor fixes.
You have to decide for yourself.
A desktop like XFCE that gets rarely updates is of course known to break less. But like I said if you continue using what we ship by default in Maui 17.03 it stays stable and solid aswell.
Though KDE Plasma also is available as LTS version and KDE Neon has a LTS ISO for that purpose. This means Plasma will only get minor fixes here and there but no real new features which are almost everytime the root cause of some new bugs.
If you use Maui 17.03 without upgrading plasma (enable the maui-xenial-backports-neon repo) you will basically have the same but without minor fixes.
You have to decide for yourself.
A desktop like XFCE that gets rarely updates is of course known to break less. But like I said if you continue using what we ship by default in Maui 17.03 it stays stable and solid aswell.