Left by a country mile, function always should be first,
KDE & Plasma users
KDE is an international technology team creating user-friendly free and open source software for desktop and portable computing. KDE's software runs on GNU/Linux, BSD and other operating systems, including Windows.
The one on the left. To me it is far easier to navigate and looks well designed for its function. The info seems easier to find. Haven't used the style on the right in years, didn't even know it still existed so my opinion might be based on what I'm familiar with more than anything else.
KDE's System Settings is way more streamlined and intuitive than even the new macOS Ventura/Sequoia System Settings, though. I'm one of the people critical of the new macOS System Settings, even though I think it is a step in the right direction and agree it makes sense to make it similar to the iOS settings app for consistency's sake. Imusing it feels like the Apple developers didn't really put much thought into how and where various settings should be accessed, imo.
Strong preference to the left. The one on the right I never know where to look. Way too busy and I always miss what I'm looking for at a glance. Searching and searching every time sucks shit. On the left, it's just a list. My overworked brain can handle that easily. Also, I prefer more angular designs over the bubbly pattern that's so common today. Lastly, when it's always there it's easier for my brain to know where things generally are spatially.
Of course, the left one does waste a good amount of space breaking from a more minimalist idea. You don't need a menu when you're already in the settings view you need. Benefits to both, negatives too. I prefer the left version.
Lastly, I do disagree with the idea that MacOS was doing a "form over function" as the function is clear. It's a waste of space and, usually, mind function to put things that are un-needed in front of the user at times they don't need them. MacOS Strives to lower the amount of visual overhead given at all times allowing you to focus on exactly what you're doing without the rest of the UI in your way.
I don't like it aesthetically as though I like minimal design I find taken to the extreme it can be too boring but it absolutely has a function.
One on the right. I have never used this iteration of the macOS settings (started using it with macOS 13) but I have used Plasma Settings' icon view and Windows Control Panel and I prefer them by a lot.
I think Plasma's would be better if it was a normal expandable tree view on the left instead of the weird expanding panels it has going on, though. That used to be a thing in KDE 4 I think.