Re: going for record downvotes... deep breath...
If someone asks me what to get, I tell them whatever best fits your needs, if its Windows, go Windows, if its OSX go OSX, if its a *NIX Desktop, then go that way.
Probably the most sensible comment in this thread. Have an up-vote.
I've tried Windows, numerous times. I have seriously given it a shot. Its lack of flexibility, abysmal package management, poor compatibility with other platforms and general fragility, make it unusable as my primary OS. Then there's the licensing.
A lot of things in Windows are hard-coded. Key bindings are a classic example. While I'm able to set up FVWM to respond just the way I like it… MacOS X will bend to my will, as will KDE… Windows stolidly refuses to accept any attempt to change the workflow — no I'm expected to change my workflow to suit it.
Package management is hopeless. There are a number of software packages I use. Can I add a simple URL into some control panel and have it automatically download and install that package with its dependencies? No. I have to go to the site and download an installer, and click through a wizard. When an update is released for a package I use, I have to go back to that site, download a new installer, and go through the whole dance again to update it. Contrast this to apt-get dist-upgrade or emerge -udN world.
Windows is one of the most antisocial platforms I've come across. Its API is completely unlike all other contemporary OSes, making porting applications a nightmare. It refuses to look at file systems which were not developed by Microsoft themselves without a third-party driver. It won't have anything to do with network protocols other than those that Microsoft invented or had a major hand in developing.
Try to bend it to your will, and, well its like trying to bend a pane of glass, it shatters. Even something as simple as moving the taskbar to the top of the screen: minimised command windows still try to "hide" down the bottom of the screen — where they'd ordinarily be hidden by the taskbar, now they're in plain sight.
Even if you don't try to customise it: the platform is such a soup of proprietary code I'm amased anything works. Even Microsoft's own updates have been known to break systems. I know people now who turn off Windows updates because they dislike the disruption to their work when Patch Wednesday delivers an unwanted present in the form of a problem that didn't exist the day before.
Ohh, and did I mention licensing? Their scheme is so complex it's impossible to know where I stand. Linux, I know exactly where I stand. I'm not talking about making changes and distributing those changes. I'm talking as an end user. Linux as an end user: if it breaks, your problem. I can handle this. Microsoft: if it breaks, your problem, and we'll be checking on you on a regular basis to ensure you don't pirate our stuff!
Servers, it's even worse. Linux: much the same as for desktops. Servers: Ohh, you have to pay for "CAL"s now. WTF is a "CAL"? Not enough to offer basically the same support for Windows Server that we get from Canonical for Ubuntu … Not enough to charge an extortionate fee for an OS license … no, we want a hand-out every time you connect a user to your server.
Then the terms are so convoluted, not even Microsoft staff can help you.
No, I'll stick with Linux thanks. I accept that for some, this is not an option. If you're into printed desktop publishing, then I can understand people going Photoshop over The Gimp; the latter has no support for CMYK, but if your needs are purely in the RGB colourspace, either is fine. Some of us at work use Windows because the software they use requires it.
Three examples. One would be those looking after accounts: Australian taxation law is that complicated and changes that frequently, I cannot recommend a open-source book-keeping package that would accurately keep track.
Another would be PLC programming, which is almost always done from a Windows environment. The likes of Rockwell might go Linux yet, but it'll take time (Microsoft's lack of direction has reportedly spooked them a little).
Then there's CAD: the open source ones are close (heck, our workplace floor plan was designed in LibreOffice Draw — no joke), but still a long way off replacing AutoCAD.
Thankfully for me, this is not a restriction. In fact, the stuff I do is easiest done under Linux. So I'll stay there. If Windows, MacOS X, OS/2, CP/M, Solaris or BeOS is what works for you, then great. Let's just accept that how we use computers is different, and therefore the platform we use is going to differ.
There is no "one" OS for all applications.