Qt (the library KDE uses) has an internal switch to use the GUI key (Command/Windows/Super/...) instead of Control, but it's only enabled on OS X. Making that a user-configurable option for other systems would go a long way. I have no idea what the Qt/KDE folks' attitude toward that would be, but I can see it as a selling point for Mac refugees, so it may be worth your while to investigate.
That would be absolutely amazing. Then the only applications on the machine that would drive me crazy would be Firefox and Chrome, since they're basically impossible to get to work correctly this way. Firefox actually let's you choose a different primary modifier key in an obscure setting, but it's not interpreted consistently.
I'll take a look. Maybe I can have some luck either rebuilding everything in a fork of the KDE Neon repos with that enabled or getting the maintainers to enable it.
edit: and LibreOffice would drive me nuts since it won't just import an exported config from a Mac that has Mac keybindings, and the export format is binary, so hard to export on Linux bulk-modify and re-import, so I'd still have to painstakingly go through its clunky interface to change everything to make sense. But still... that'd all be a huge improvement over the current state of affairs.
