I grew up with Macs and was trained on them in college using ProTools and such... but almost all of my personal DAW's were PC's. I still use a Mac for internet, but last year I used a PC for internet.
I think people who are used to Macs should stay with them. I often help my dad use a PC because he is mainly only used to Macs. He really struggles with basic tasks on a PC. He's not stupid, but it's just so alien to him and it's easy to tweak things the wrong way. And the issue with viruses and such is rather scary since he doesn't quite know what he's doing. Thankfully he has a decent anti-malware software package. And thankfully he isn't requiring the power and realtime stability of a DAW.
I go with PC's for my DAW's because I really like to customize my computers and operating systems extensively!!!! However, it really takes a lot of time and patience and very very careful tweaking and many many safety backups of partitions so you don't mess everything up permanently. Also it's important to do constant research and to learn how to keep everything compatible with each other in terms of both hardware and software and power supplies etc.
The PC OS I like best is Windows XP SP3. However, I have dabbled a little bit with Linux as well. I am possibly going to update my internet computer with Linux in a few weeks instead of Windows. I tried some Puppy Linux CD's along with some other distros and I kind of liked it. Windows on my internet PC worked fine, but I was always slightly nervous about malware or network/firewall configurations screwing things up.
I don't think I will ever allow internet on my DAW computer.
I've tried Windows Vista and Windows 7 and I really really don't like them. I wish there was a 64-bit Windows XP 2012 instead. The modern Mac OS's are OK to me, but I don't like the limited amounts of software that runs on them, and I don't like how Apple does business. Apple seems to be a control freak
type of organization that slows progress just to make more money off of proprietary hype items.
So really the next time I buy a new computer I'm kind of in a bind. I don't want Windows Vista/7 or it's derivatives. But I don't want to buy into the expensive and limited Apple paradigm either.
If I knew Linux well enough I'd go that route, but every time I try Linux I hit a wall because of unfamiliarity with some basics about how to configure and customize or troubleshoot stuff. And again, some of the software types are limited in Linux.
I really don't know what a person is supposed to do these days if they don't fall into the "right" category. Maybe I'll ditch the computer next time and buy dedicated DAW hardware for a change, like I did way back in 1993-2000.