[phyrrus9]

Open-source, some distributions are managed by the community(e.g. Debian) and some by large companys(e.g. Ubuntu)

When you buy a Mac, you know that the hardware is fully supported by the operating system.

With Windows, Linux, BSD, etc you're taking chances. Most hardware are supported by Windows, some are not by Linux. I don't know much about BSD. You don't have to worry about this if you're using mainstream hardware such as Intel CPU's and AMD/NVIDIA GPU's as they're so popular that they're probably all supported by now.

An open-source operating system such as GNU/Linux is the most customizable you can get, because the source-code is freely available to you and everyone.

Actually, OSX is supported on non-Apple hardware and will run quite well on an IBM T series computer. The majority of OSX is open source by Apple, the rest is either private or BSD code.