Windows 3.1 is better than earlier Windows, but I haven't seen a claim that it's better than Win95?
I don't really think 3.1 is eye-searing, but I think the basic design is pulled forward from 3.0 which ran on mostly any video card, but feels designed around 16 colors. Wikipedia says 3.1 requires vga, but they didn't make things pretty by default until 95.
Of course, all this is a matter of personal preference—I just think that nostalgia plays an underappreciated role in these discussions.
For functionality. I prefer modern control panel over 3.x - and over Settings.
1) Settings has no applets I can pin to the start menu (ex: printers).
2) I can't be in two parts of Settings at the same time.
3) Commonly-used control panel options: In Settings they can be missing, neutered or moved+moved again.
4) Settings still reverts to control panel applets for some functions. Will those options still exist without a control panel? No one knows.
And the same is true for the settings app. I never really use the Control Panel–specific settings, and whitespace doesn't bother me, so I'm not inherently opposed to the new app. But the execution just feels subpar somehow—if I had to guess, it's probably the latency whenever you click anything.
(macOS also has all kinds of weird UI bugs too, e.g. the Bluetooth and sound dropdowns in the top menubar are very finicky for me. And System Preferences proper isn't much better. It drives me crazy....)