<rant>
PC, Hands down, that way you have the freedom (not to mention a HUGE price break) to install what you want. If you want Linux, or Windows you got it.
Mac does have its place, that place is for those who think they are too good for PC, or those who think that Mac is easier than Linux or windows, which it is not.
There will always be Mac Fans, I will always push them down to the ground because they are so ignorant of how much free stuff you can get for windows / linux and how much Mac/Apple likes to put you in a box and drop little dukies in with ya. Example: OSX: they hide functionality from you until they think it is the right time to release it, people find it and cause a big fuss. iPods/iPhone: They crash often, You void your warranty by changing your battery.
I am not a big fan of Windows, it crashes lots, updates suck, etc. However Linux is the wave of the future and all those poor Mac users who think that their Operating system does not copy anybody, THINK AGAIN. Mac has been copying Linux distro's functionalities since they moved to their Unix based Operating system.
The reason Mac had to start going with Intel is because they could not compete, so they joined the club and tainted the goodness that is a PC. Macs are essentially broken PCs, you HAVE to use their software to do anything on it, you are not free like you are on linux.
To each their own, however 90% of the problems that people come to me are from fellow college students who have Mac computers, they get a virus (YES THERE ARE VIRUSES FOR MAC), their iChat crashes anytime they receive a file, Their iDvd keeps burning dvds that do not play in most dvd players, etc, etc.
Linux is for those who have guts to do things and be able to customize just about everything about their operating system. Yet linux is also becoming the easiest operating system to work with not only programming wise but also from a regular person's point of view, such as my parents or my non-techy friends.
</rant>