This article from PC Magazine is interesting. It does a fairly good job of looking at the pros and cons of various OS’, without the silliness of most such discussions. The only aspects of it I think are a little unfair are the “Price” and “Installation” scores, both of which rate Mac OS better than either Windows XP or Vista.
On the price side, while it is true that you can buy Mac OS for less than Windows, you cannot (at least if you are a typical user) install it on your existing, non-Mac hardware. So the true cost of a typical user switching to Mac OS includes the cost of buying a completely new computer, at a premium price.
On the installation side, again the comparison is not quite fair. Both Windows and Linux are general-purpose OS’ which have to be able to install on a wide-range of hardware and almost unlimited permutations of hardware configurations. Again, Apple does not have this problem with Mac OS, since Apple tightly constrains (though not as tightly as it used to) the hardware configurations with which Mac OS must contend.
Overall, though, not a bad article.