Windows Defender while not being great, at least means you don't need to start off by installing a third party Antivirus. DirectX 12 also comes to mind.
But that's about it. For regular users, Windows 7 has been the best, and after noticing how my parents struggled with the updates, nothing can convince me to think otherwise.
All the really nice bits of Windows 11 are lost to time because you don't notice them, but they all add up. The fact we're mainly worried about telemetry over anything else says it all.
Visual Studio is a good IDE, but at least back in the day it needed ReSharper to have the smarts that Jetbrains IDEs usually have. And the fact that it only works on Windows is a dealbreaker for me, as many people want to develop on the same operating system that they target for deployment.
I can certainly buy into small improvements, such as Notepad having tabs. And I'm not the one that mentioned telemetry. But now that you've mentioned it, I'll say ... such marginal improvements aren't worth the creepy spyware, or the ads, or the useless breakage in UX.
(Sorry for the snark but I couldn't resist)
Dark theme
HDR support
Auto HDR for many older games
Native system wide support for surround sound in headphones with hrtf
Win+Shift+S screenshot tool
It took a long time to get here, but the settings app is now better than the old Control Panel imo
If you're a gamer then HDR/surround/raytracing can potentially be huge upgrades if your hardware supports it.
Night mode, dark theme, and a decent UI are things shoestring Linux distros can pull off.
Nowadays it's impossible to know exactly where some specific setting is anymore, and the settings app has been so dumbed down that most settings don't even exist anymore. Just the other day i tried to fix my dads touchpad and went on a wild goose chase through every possible setting location, of which there were too many, and kept coming back to the "settings app" in which the touchpad "settings" had only a single checkbox, fully unrelated to anything actually useful at all. The tab was there but there was no fucking settings in it. Nothing useful at all. In the end i tried driver updates, i tried rollbacks, i tried every setting app, i tried everything and the touchpad still doesnt work. You can click, you can't move, you can't scroll. The man didn't install anything, windows released an update and the single most important tool for interacting with the computer, one that is built into the hardware, was broken with no recourse to fix it, I'm simply not allowed access to the settings i require to maintain my own control over a functioning device.
That is the new settings app to me. Maybe if you stay within the ever shrinking bounds of control that Microsoft so graciously barely allows us to utilize, maybe then the buttons are rounder and the categories are better laid out. But if you need to fix anything that exists even slightly outside that toddler playground Microsoft is only ever making that more and more difficult under the guise of UI "improvements".
Windows has had themes/color schemes since 3.0 - yes the early 90s
Ray tracing has nothing to do with Windows, either
Drawing the line between the OS and "not the OS" is really difficult. Direct X is included with the OS and DX12 is not compatible with Windows 7 so basically DirectX 12 is something you did not have in Win7 and do Have in Win10.
Much like Apple and Linux, windows even though it always had an API for it, supports Virtual Desktops finally.
Not much apparently. The funniest: icons like chrome, round corners like mac.
edit: On the up side, Bing is actually much better than Google now.