As other have said, a combination of Firefox PDF tool, PDF Arranger and Xournal++ is all I’ve ever needed. And Okular is nowadays my viewer of choice, which does a lot on its own, too.

KDE.

It would be easier to just try the live systems (booting from USB).

Changed to Cinnamon (Linux Mint) after GNOME 3 and Ubuntu’s Unity went bonkers, then changed to KDE Plasma some years ago.

I think KDE is constantly working to improve the desktop paradigm. GNOME tried to change the paradigm… I didn’t like what I saw. I’m too old to learn new tricks.