Microsoft Windows is so stupid. it created a myriad ways of the control panel.
There's the classic WinXP interface. Then vista interface. and Windows 10 added another.
The best UI is just 1 way to get to an item.
@alvarogonzalezsotillo there r few issues. One is whether we r focusing about GUI. (so, this excludes discussion about command line or scriptable UI, as another topic)
for GUI, there's 2 things. 1 is the design of the GUI. The other, i was mentioning, is the multiple ways of grouping or navigating to the same set of buttons that launches the apps. MS has 3 versions of this roughly, in XP, Vista, and Win10. And, all 3, are still available and shows in Win10 depending on how one got to them.
@xahlee
I think there should be at least two UI.
One should be discoverable and graphical, for newcommers/casual users (for control panel, I prefer windows 7)
The other, scriptable and composable, like WMI.
Maybe a third one is necessary, for keyboard less devices.