MAC > WINDOWS > LINUX

Mac > Windows > Linux
I know, it's not what you want to hear. But Mac OS is stable, secure, and has tons of free, easy to use, and open sourced software. There's really no reason to use Windows or Linux, which aren't as easy to use.

Mac is more secure than Windows
Mac is easier to use than any build of Linux
Mac IS Unix
Mac has open source elements
Mac software is easier to use, better looking, and cheaper.
You can run any windows or linux program in Mac, through the use of Wine or Crossover, or, worse case scenario, virtualization.
There's more software for Windows than Mac, however, it's mostly crapware. Free software for Linux or Windows pales in comparison to Mac software

More game developers are producing for mac now too.

Macs, with their new use of the gpu as a general cpu (Snow Leopard), are faster

And, as for hardware:
Macs last longer than PC hardware
Macs have better components
Line up the features of a Mac to a PC, and the Mac is cheaper
Macs are thinner, lighter, and have longer battery life
Macs have better support, and MUCH better customer service

Business wise:
Mac market share is growing
The economy has hurt all the other manufacturers much more than Apple
40% of college students want an Apple branded computer, which is much higher than any other brand desired. (Up against HP, Dell, etc).

And if you don't like Mac, it's just because you're too afraid to switch.