Generally, I don't think Windows 10's telemetry features are privacy-violating. Most of the telemetry (especially if you choose the "required only" option in setup) is just for crashes and basic usage data (they won't use it for advertising for example, like Google or Facebook); that said, I use pi-hole as my DNS which blocks a lot of the Microsoft URLs used by telemetry.

However, my biggest issue is simply bloat. With every major update on Windows 10 we get more and more crap running on the OS. A fresh install of Windows 10 21H1 uses 3Gb+ of RAM and that is insane. There are things like "YourPhone" which is an app that starts at boot and cannot be uninstalled which is supposed to help integrate your Android phone - I have an iPhone and couldn't use it even if I wanted to, but I still pay 4Mb of RAM for having it running. I can probably disable half the services that are set to start automatically and still have a working OS.

Tried using something like winreducer to actually strip out the binaries instead of just turning stuff off via registry, but it's tedious; nowadays I just do a regular install then go into task scheduler and remove 1/2 of the needless crap then manually disable 1/4th of the services and use some PowerShell scripts for removing un-removable apps.

I miss the good-old days of Windows 2000 where we booted the OS with < 90Mb RAM and a couple dozen processes.