Choosing an operating system has some definite parallels to choosing a religion. For most people it's a default choice, what they were raised with or what the people around them evangelize. It's impossible to know ahead of time the full consequences of one's choices, it's also unlikely, unless you're a technical expert in the field of operating systems design, that you can make a truly informed choice based on the merits of competing offerings.

An OS embodies assumptions about the nature of the world and the nature of the people using the system, these assumptions often place constraints on the design of applications for a particular operating system.

Disputes between users of different operating systems are referred to as HolyWar''''''s for a reason.  Religions and operating systems are both competing for the same resource, the involvement and energy of people who can extend and strengthen the CommunityOfPractice they represent.

''There are more objective criteria for deciding which operating system to use than there are which religion to practice.  On the other hand, it may be that the metrics used to convert those criteria to a ranking are equally subjective.  People with similar metrics may find themselves favoring similar OS's.''
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This characteristic holds not only for religions and operating systems, but for "ideologies", i.e. transmitted / shared ideas in general. After RichardDawkins they are called memes. See the discussion starting at PatternsAsMemes.
In my opinion the difference between an idea and an ideology was caught best by the author of the book "Viruses of the mind", the former author of Microsoft Word, in the sentence: "An idea is something you have. An ideology is something that has you." -- DavidAndel
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I spent about 4 hours at the Eugene-LUG last night installing S.U.S.E on one of my boxes, which is what crystallized some of my thinking on the topic. --LarryPrice