Windows and Linux both have there pros and cons, and i will agree BSD is a decent OS as well. I have used Knoppix, and Redhat 8/9 Linux is very similar to Windows these days, and is more secure. But i don't know if it will stay that way, in the same way FireFox and Mozilla were super secure because noone was using them. The more popular something becomes the more likely it is to be attacked.
The Mac/Apple OS is definatly a clean operating system, i will give it that, but for those who have gotten used to the windows system, it will be hard to give up your right click... the right click has become a staple in OS' these days, and i have seen patches, and drivers for similar features on the MAC, but it never led anywhere good... too unstable, too many missing peices of code to implement such a large item in a single patch.
As far as daily use, i prefer Windows, when it comes to networking or protection I either use my laptop or live www.knoppix.com
cd to use linux instead of installing on my desktop... windows and linux don't always like each other... so i've avoided it on my main computer.