oi where's bsd :(
no os x doesn't count
I feel the same. I'm hoping to be switch to FreeBSD shortly enough, after I scrounge together a better system (in regards to hardware compatibility). My only issue is how soon Vulkan would be supported when it's eventually released... I'm also a bit wary of how well Nvidia supports FreeBSD and how long they will continue to do so.
My largest issue with Windows is it very possibly becoming a subscription-based software in the future. Microsoft seems to be moving in that direction, with perpetual updates for Windows 10. Obviously that's not business savvy, so that's why other sources of revenue are being tested already; there's already ads integrated into various facets of the operating system. I'm not fond of the data collection, either, though I wouldn't call it "spying" yet, because it is claimed to be anonymous, but since the data can't be audited, there's always an issue of trust...
I'm also not fond of how uncustomizable Windows is, from the perspective of a programmer (or even power user). I've recently had the whimsical idea of having 3D scenes as a desktop background, but that's incredibly difficult to implement and involves a lot of reverse engineering and a lot of unsupported API usage. And whatever works today could break catastrophically with a Windows update. Not to mention poor theming support for anything but the default style...
As far as Linux distributions, I'm primarily opposed to licensing model. Although I find knowledge as a commodity morally wrong (i.e., patents and copyrights), I also feel forcing such a perspective in a largely capitalistic world at this time is extreme and unfeasible. As well, BSD licenses allow more freedom to the developer, for better or worse. As it stands, you get commercial entities that abuse dual-licensing the GPL with a propriety license, which perverts the purpose of the GPL...
I'm also not fond of the Linux distribution model. Linux is just a kernel, not an operating system; each installation is its own separate monster, composed of customized patches, different version of said kernel, and a different userspace. It's just not cohesive, which detracts from the user experience. Each distribution also has varying documentation quality... From an outsider, FreeBSD (and other BSDs, as well) has immense documentation, and it feels much more coherent as far as configuring various aspects of the system (especially networking bits) and using the system itself, while Linux necessitates referring to the community (either by asking of searching discussion forums).
I do very much prefer the keyboard-centric configuration/usage methods in BSD and Linux compared to Windows. The shells are superior, as well (I use Msys2 on Windows when I need to use a shell [largely because I don't like PowerShell's syntax and Bash has better support in open-source software]; still, it's built on the Windows command prompt, which introduces plenty of quirks). Most GUI software is poorly designed on all platforms due to appealing to the lowest common denominator (an average user), especially configuration software... So you either get simplified UIs on Windows or poor UIs on open source software.
In the end, still not being a FreeBSD user, I prefer FreeBSD's native software, especially the choice of clang instead of gcc. I also find FreeBSD's jails feature amazing (I genuinely wish Windows had a similar feature), though I suppose it won't be that useful for a desktop user as it would be on Windows. FreeBSD's memory management is better, in my opinion (deny memory allocations rather than kill applications when the system approaches memory exhaustion). And most importantly, the documentation and coherent structure of the operating system, compared to Linux distributions and perhaps even Windows.
I can't comment on OS X, having never used it. I used Mac OS 9 in Middle School and thought it was neat, I suppose; but that's a completely different platform than OS X. I'm also amazed how Mac OS 9 was essentially built on assembly and some Pascal... Truly bizarre compared to most any other popular operating systems in comparison.