I use windows, so i vote for that.
As good as macs are, or people say they are, they Don't have as much things that you are able to do on them. Like downloads, you can't download EVERYTHING because there isn't a mac specific version for it. For windows there isn't EVERYTHING for download, but there is a lot more than mac.
I picked Windows because it's what I'm used to.
The compatibility of the things I want to use on a day to day basis is better..
And I really love PC gaming.
I've tried using Linux based OSs before and it's just not my thing.
It feels smoother and such, but yeah.. that's about it for the high points IMO.
'course everyone likes different things. =d