Greg
I run mostly vanilla(Gnome) Ubuntu, not the KDE flavor (I did try it a while back) . I use gedit for basic editing and Libre office for other stuff.
I am not an Author.
I am not a (modern) coder. I just peek from time to time

Sigil does what (and is closest with the [I]feel[/I I want)] I need (with Calibre catching up fast).
I use the term
feel because it is more about matching your thinking and working style than being 'better'.