Define what you mean by "productivity possibilities".
If you mean in the sense Windows has more software support than other OS, I agree with you. More Windows public = more money, so obviously the SW companies would develop mainly for them.
Still their perfomance , aside for gaming, are not as overall effective as a UNIX based system. Most supercomputers and servers runs UNIX based systems for a reason.
I have several years of experience in IT, and I have tested all the main systems. Each OS has its own strong and weak points.
MacOS
-Ideal for multimedia work, especially graphics (Photoshop on a Mac is beastly good). Intuitive to use, fast, UNIX based for security and powerful computing (the MacOSX code is based on BSD and Linux code mixed with some proprietary one) with support for professional SW. You get some UNIX tools, other you can port them with Macports. Integrated OS and HW for best performances and standard rules for apps developing, but this approach limits the customizing and control over the OS.
Many graphics companies buy Macs.
Linux and BSD
Both UNIX based systems, both opensource.
Their commands are similars.
You get full control over the system, you can modify the code and fully customize it to your wishes.
You lack the presence of some professional SW like Photoshop.
However you get many useful free SW to make up for it, some movie companies use only Linux with SW like Blender (3d animation, etc...).
Mainly used on servers.
Windows
Good for gaming. Precaricated with most non-Apple HW, huge choice of SW and HW accessories.
Not very secure unlike UNIX systems.
They starts with a good initial speed that keeps decreasing as months and years passes (unlike UNIX machines).
Often Windows servers crashes and you need to reboot them quite often, unlike Linux and BSD servers with can stay on for month and years without crashes.
7 it's mediocre compared to UNIX based systems, but not to other Windows systems. In this sense for a Windows system is actually pretty good, especially if you compare it to the flop it had Vista (without SP1 it sucked badly). However I don't find 7 that stable. Sometimes I had to deal with cases where the applications icons went blank by itself on 7 and the program stoppped working, reinstalling applications and so on for example.
I find XP to actually be more stable.
Popularity is not equal to a powerful system in the first place.
If all the people started to jump down from a bridge, you would jump as well? I sure wouldn't.
Most supercomputers and servers runs UNIX based system, not Windows.
Then to each one his way.