My opinion is that the privacy concerns surrounding Windows 10, though some are absolutely legitimate, are mostly scaremongering and have said so on these forums many times.
You can refuse to use the personal digital assistant feature of Cortana (I do refuse, but not due to privacy concerns) and not use the other apps, including One Drive, that involve the exchange of your personal data with Microsoft [one can't really use cloud storage of any variety without consenting to the storage entity having access to one's personal data - having access does not mean giving permission to disseminate]. I tell everyone that the first thing they should do after installing Windows 10 or starting up a brand new machine with Windows 10 is to spend whatever amount of time they require to go through each and every one of the panes under the Privacy settings, read the "learn more" links for each if necessary, and then set these according to one's personal desires.
For myself, I have things pretty much "locked down" on the privacy end of things. That being said, I want to be logging in with a Microsoft Account. The advantages to me of having something that does log the software I've purchased from Microsoft and have a license for is alone worth its weight in gold. If you're ever faced with a case where you need to actually reinstall Windows 10 it makes life so much easier when you go to reinstall, say, Microsoft Office, and can't find your original installation media [if you even had any] and license key. All of that stuff is kept in your account and allows you to download and reinstall these programs with ease. Were I using multiple devices with Windows 10 where I set up my own account having the synchronization feature across devices as far as settings, sessions, etc. (depending on what I pick to synchronize) is also something I love. I find sync features in Firefox and Google Chrome to be worth their weight in gold and I am under no delusion that anything that I do in cyberspace is, in any conventionally meaningful sense, private. It never has been.
Even if look at just what's a part of "the public record" legally, and that's now searchable via the web from virtually anywhere, things that our parents and grandparents thought of as largely private (e.g., property purchase and sales records) can now be looked up in seconds. Much of what we thought of as privacy was the direct result of it being tedious to find information that was part of the public record. Searching public records has been a cinch for decades now, and you find any number of companies out there online who will compile those for you in seconds on anyone you wish. As a result I don't really feel that we will ever have anything approaching the sort of privacy that was common in the past. That ship has sailed. It will only be things legally mandated as private (e.g. medical records) that even have the vaguest chance of remaining actually private, and even those could be hacked. One cannot touch cyberspace and have any expectation of privacy as it was once construed.
Brian AKA Bri the Tech Guy (website in my user profile) - Windows 10 Home, 64-Bit, Version 1803, Build 17134
In a modern society where everyone thinks their opinion deserves to be heard nothing annoys me more than individuals who mistake their personal preferences for fact.
~ Commenter TheCruyffGurn on the The Guardian website, 8/13/2014