I find OS X to be generally superior to Windows, both technically and in the user interface. However, Apple products are more expensive compared to IBM compatibles and they have less third party support - although the software that does exist for the Macintosh tends to be quite good, especially the software first developed for the Macintosh.
I own both a Macintosh and PC desktop. The PC is nice for games and the wider selection of software (for the more obscure stuff, ultimately), and the Macintosh is nice for everyday life. The Mac would work fine for games, too, except that there aren't many Mac ports.. and running Bootcamp on a Mac is pretty pointless
As far as Linux, OS X is built on Unix as well, and it's semi-open source.. it's not free (not really), though. Linux is sort of PC+Mac - very solid OS foundation, literally decades of software, much of it free, but if it doesn't work on your system you'll have to dig around for a while to figure it out.. and Linux does feel faster than either OS X or Windows, at least Ubuntu 10.X did, never tried 11.. for me though, Linux just doesn't have that broad base of really good software.. and I always run into some issue with my max monitor resolution not being supported, and I try to edit the various mysterious .config files and it never works, or I can't quite get two monitors to work, or my ATI/AMD GPU isn't supported, etc. etc. etc.. I don't have those sorts of issues with Windows or OS X. Still, for raw speed, Linux is the best.
Overall, I'm glad we have OS X/Macintosh, Windows, and Linux/Unix.. they have all influenced the others, making them all better. The Windows filesystem UI was quite horrible until MS finally took the plunge and copied Macintosh (who originally copied Xerox anyway..) and Unix is the original popular multiuser/multitasking OS.. etc etc etc