I like to stick to good old Windows.... So I have a Mac computer, but I use the windows disc thing that can transform your mac partly into a windows... It's awesome.
I'm a PC kind of gal. Macs always seem to find a way to screw something up for me. Like, I had a presentation in one of my classes and the only computer they had was a Mac and on that day it decided not to work. So, yeah, a few bad experiences on my end with them, so I'll just stick with Windows.
Windows because its more opened to developers. The possibilities with Windows are endless. Mac is better for just basic computing, Windows might have more security issues, but thats just a price you have to pay for being more opened to Devs.