I used to be a fan of Microsoft. Now I am one again.
Here I'm stuck with Windows 8.1 for now as it's by far the best performing and the most efficient OS for my workload on my hardware (Athlon BE2350 2,1 GHz, Radeon HD 3650, 4 GB DDR2 RAM) - pretty bad, huh?
So what I would really like to see: Macbook Pro (it runs every OS and you don't need to use Hackintosh to test OS X). Then do CPU benchmarks, game benchmarks (including Source engine/other Steam games), disk performance benchmarks, power consumption tests using OS X/Linux/BSD/Windows.
I have come to an interesting fact recently when I ran some benchmarks on the BSD system. The CPU load was lower than on Linux yet PCBSD lead to better FPS in unigine sanctuary on GT 520 nVidia card (Im not a hardcore player, just a gamer/game collector). Also I noticed that on BSD I don't have all the "freezes" that Linux gives me. To me it seems that Linux extensively uses CPU. I know that X server is also acting up a bit here. Still I don't know why I need a Core i5 to run the today's Linux system at reasonable speed.
Another thing: on Linux (on BSD it was even worse), when browsing the web using Chromium (other browsers do this too), websites are often messed up/different than on Windows and sometimes not as fast. Again it sometimes freezes and I see 100% CPU usage. When scrolling, I see really bad tearing too. I can run WebGL (aquarium was 1 frame faster on BSD than on Linux at similar workload). This is a feature I'd also like to see tested: web browsing. We all know that Windows/OS X are going to outperform others, right? So this is just to draw atention to the most common task not being supported well by Linux/BSD systems nowadays.
On underpowered hardware which I have I really feel every single slowdown in every OS. I am very sad to say this, but Windows 8.1 outperforms them all (that's the way my brain feels it, benchmarks are just numbers and can be fooled)
One more thing: I hate Android. It's the worst performing OS I've ever seen. WP/iOS ftw xD ... Just saying ....