To be fair, can you name a corporation that genuinely regards privacy as more important than profits?
The only way I can see that happening is if they believed that a privacy breach would destroy their business model, i.e. badly affect their profits.
Anyway, back to the OP's posts:
I see a confusion between encryption and security. The truth is that while there are old or cheap & shoddy android phones, the encryption of a modern android has all of the capabilities of a modern iPhone (including hardware-backed secure credential storage). That's why I assumed you were referring to malware (hence the reference to curation of the app store), because they do have an advantage there. But that's easily separable from the OS, though you do need someone you trust more to manage it, and who has the resources to do a better job (not as easy as it sounds, especially because you need network effects to build it successfully: think how Microsoft failed with their phone OS, where part of that was a vicious circle between lack of apps and lack of users).
However I'm still not clear where the iPhone comes into this? Are you planning on using Apple hardware? If so Apple will fight you rather than cooperate. And once you hack it to replace everything then you aren't using their security any more anyway (in fact you've had to break their security to do this). So I'm going to forget the Apple aspect.
But then I don't see why you think Microsoft handling phone accounts will make them more secure than Google. Account hacks are not significantly due to a weakness of Google's systems, but weakness of the users: they use simple passwords, re-use passwords on different sites, divulge them to people, don't enable half of the existing security tools. And frankly Google accounts are a more attractive target than MS ones: there are more of them, a wider range of people have them, people keep a lot of valuable information on their phones. I really doubt that changing one corporation for another would make a lot of difference.
The merits you claim for a phone-PC binding all seem to be things you can do already if you want (and not all do). Don't forget how many people don't have a PC (or have but don't use Windows). To me the fact that android doesn't try to link itself to a computer platform is a merit, since it's essentially equally accessible whatever platform you use. But really this sounds to me like you personally have an investment in Microsoft's "ecosystem" and would like your phone to be better integrated into it - which is fine in itself, and some people like that sort of thing. But if it's as attractive as you think I wonder why MS weren't more successful.
But really the practical point here is who is going to run this project of yours? Not Apple: with them you do it their way or no way. Not Google, you seem clear on that. You could build your own Android from the AOSP (for specific phones that meet your requirements), but are you expecting MS to collaborate with your binding or do you reckon you can bake enough of their tools in yourself? Who is going to manage your app store linked to an MS account? Basically are you hoping to pitch this to MS or are you planning your own fork of Android with MS integration, and do you know what that would require? There are a range of alternative mobile OS projects out there, so you could do worse than study them to see how easy this is (try Sailfish, Graphene, and the history of the attempt to spin CyanogenMod into a commercial project, for examples).
Now this may be off-topic "chatter" to you, but let me just add that I do regret MS leaving the phone market. There were things about their phones that I liked, and they took a distinct approach. We're poorer for not having the option.
