Basically with Windows 10 I feel like I have no rights. I cannot make any claims for sure about this, it's just my but after reading their EULA and many articles about it, I get the impression that Microsoft is accessing all of my data - logging my keystrokes, sending my documents to their servers, and basically snooping around every single thing I do.
Be careful with all the FUD out there. And Microsoft has previously not done a great job separating its cloud services TOS from the Windows TOS. Also, the Windows Insider program (basically for the beta testers) is far more invasive than for normal users IMO. I'd also say the Apple EULA doesn't make me feel much better than the Microsoft version, but the fundamental risk in either case is probably what you store with them in the cloud rather than what you do on your system.
I want a computer and an OS that certifiably:
Has no keylogger.
Does not transmit any of my files (that I create) to their servers.
Does not "sniff" through any of my files on my hard drive.
Does not collect, gather, or know about any of my potentially sensitive data.
I hear you. But just to put this in context:
- Neither Windows (non-insider) nor macOS have a built-in keylogger in the devious sense. Both can transmit keystrokes back to their respective parent companies depending on how they are configured - for example using the search/Cortana box in Windows 10 and using Spotlight with Spotlight Suggestions enabled. They both do this to provide more, online, information as you type. Fortunately, you can currently disable all of this.
- In the malicious sense, neither OS "sniffs" through your files. Both OS' index your files for faster searches, and both allow you to exclude locations you consider sensitive. On Windows you can disable Indexing; disabling Spotlight on macOS has some side-effects.
- From what you said, your last requirement must relate to document data rather than, for example, your location? If so, turning the diagnostics or telemetry down on each platform prevents raw data of this kind being sent.
It may sound like I'm defending Windows, but I'm really not. I too wish we had more control - which is in fact the whole reason I've looked into this sort of thing so much. I moved to the Mac many years ago, but I've been evaluating Windows 10 because although in many ways macOS offers a better software experience, I dislike hardware that I can't maintain myself (so I'm currently still on a mid-2012 MBP).
As part of my evaluation, I set up Windows 10 FCU in Virtualbox on my Mac host using a bridged network, and then used Wireshark to monitor network traffic both from macOS and Windows to see for myself what was being transmitted where. Of course, Windows required a fair bit more configuration than macOS - from removing all the bundled apps and live tiles (because they update in the background) to disabling Cortana via Group Policy and so on.
macOS is much easier to get to a reasonable state. Then I used each for a few days, but avoiding anything online - so just working on local documents and so on. From what I saw, the platforms behave very similarly. So they both do a lot of what you'd expect: NTP updates, register for push notifications, pull weather information (if you leave the appropriate Weather app/widget in place) and so on. The only major difference was that Windows would frequently download Windows Defender definition updates, and would connect to the Microsoft telemetry endpoints every few hours. Some information I read online claimed that these connections even bypassed the hosts file, but I found I could disable them via the hosts file in my VM. Perhaps something changed between the (frequent) Windows rollouts.
I still stand by what I said - the actual difference between the two platforms, once configured correctly, is only very marginally better for macOS. Remember that Windows 10 is HIPAA certified and so on, so there's that. For me personally, my trust issues with Microsoft are not so much privacy and data harvesting (all large companies harvest data if you allow them and Apple is no exception) - it's that Microsoft can't seem to pick a coherent overall strategy and stick to it.