If anything Windows 8 and OSX are the closest. (Start Screen = Application Launcher); and the taskbar and dock continue to converge.
Disagree completely. Windows 8 Metro is closest to iOS if anything. I use Windows 8, Windows 7, XP and OSX daily. OSX's basic interface conventions are far more similar to older versions of Windows than Windows 8 Metro is to older versions of Windows. And since you can't really get rid of Metro satisfactorily without third party help I stand by my statement at least for the time being.
But transitioning form 7 to 8 isn't hard either. It's far easier than transitioning to OSX because once they know how to find and launch a program in 8 it looks exactly the same on 8 as it did on 7.
Except that "find and launch" bit is a pain. Do you have any idea how much time I've had to blow explaining the differences between 7 and 8 to people? 8 is designed for touch screens and not a single desktop or laptop computer we use has or needs a touch screen. The apps are the same but I still have to interact with the file system and other OS features regularly so that doesn't mitigate the problem at all for me.
I agree it needs about 5 - 10 minutes to cleanup its settings to make sense on a default, pin what you need, cleanup the live-tile overload on the start screen, tell it to boot to desktop, and use the desktop versions of the photo viewer, etc so you aren't being thrown into "Modern UI" at random all over the place. Turn off the extra hot-corners, etc.
Which most people I know are never going to do. Maybe you work with more computer literate folks than I do (wouldn't be hard) but I generally see the defaults left at whatever they are. Any system that requires that much clean up is something I have NO interest in using.
But you don't need any third party utilities or anything to make Win8.1 a completely serviceable desktop OS. I'm at this point indifferent which one I'm using.
Personal preferences I guess. I truly cannot stand Windows 8's interface. I find it clumsy, badly designed, and it generally just gets in my way. I'm not the pickiest but it makes even things that should be easy needlessly difficult in my opinion.