In the mac vs pc vs *nix/bsd it all comes down to end user customization.
Apple wants to control every aspect of your user experience so if you look at the phone there is plenty of stuff to look at and but if you want to change something about it you will be hard pressed. Apple says this is for stability. Which is true. Also Apple products are much easier to use (this has been proven). I would have no problem giving a less tech savvy person an Apple product to use if I wasn't around.
In the Windows/PC world (including WinMo in here too) customization is an option but most will be happy with just changing the background on their desktop. However those that want, can tweak and install a multitude of programs run lots of different things and much more than a mac can. Windows is the lumbering giant and I would have no problem handing a windows product off to almost anyone (winmo excluded here, although it does have it finer points.)
As for *nix/bsd community they are set up to tweak the ever living crap out of anything that moves. They hack, slash and dice their way through a command line so the transition seems more smooth or every time they press the f key it makes a fart noise. If there is a piece of hardware or at least something with a screen a linux/bsd developer will wonder quietly to himself, I wonder if I can put linux/bsd on there. It's all about sheer power over the OS. However with this power comes a much less user friendly rough around the edges user experience out of the box.
In the end it all comes down to what you want.
Apple
Pretty, simple to use, few options, use only their hardware
PC/Windows
Less pretty (but not by much) lots of options, easy to use, can use a multitude of hardware options
Linux/BSD
Can be more pretty or less, steep learning curve, more options than you can possibly imagine, if it's hardware it can probably run a kernel.
