Everybody has their content for the Rift. They were first. And it shows by the number of people making content.
The Vive is pretty awesome. The controllers are top notch. I was playing (edit: nope, not Incredible Machine) Fantastic Contraption, and having a great time at it. Things just work, and work well. Make sure to put the room position sensors up about 5-6 feet on tripods though.
The OSVR... Well, a pile of crap is putting it nicely. The scripts that install the drivers are that: bad scripts. half the stuff is command-line and badly documented (unless you go through source as your documentation). There's almost no applications for the platform, and no way to run Oculus based demos and games on it. Head tracking was a disaster- when it worked. Save your money and frustration. Buy something else.
Not a problem, not even by default with the latest Oculus software. SteamVR supports Oculus, not sure if the inverse is true (although I will be finding out with my Vive purchase).
> Sorry, no X86 apps.
Not a problem.
> Very little applications for platform.
Somewhat. Virtual Desktop implies that you can use any Windows application - but purely native stuff is still scarce. When you get more specialized with stuff like Leap Motion Orion (which is outright mindblowing), the situation becomes much worse. All the cost of living on the bleeding edge: the devices themselves are extremely polished but the community surrounding them is still miniscule.
> Loads of crypto data going to and from MS domains.
Oculus tracks. Nothing reported in that department for Vive.
> No Administrator access, nor is there even a file manager.
OSVR somewhat blows this door open, although not yet. It's really new and understandably janky - I steer well clear of it. Still, once it's more mature, it's going to be great.
> Requires Microsoft account to use, full stop.
I can't recall if I had to set up an account for the new DK2 runtime. Vive requires Steam.
> If you're prone to getting migraines
VR is known to have motion sickness problems in specific titles (which move/rotate the camera) for some people. I am not one of those people: test a kit out before buying. I've never heard of/read about migraines with VR.