I chose linux for a reason of all given.
I think it mostly comes down to these three, in order of importance:
4) Open source
number 1 is most important because usually I usually install linux when windows fails and I don't have a windows repair disks (yeah there's other methods to get windows, but I don't trust them). Most modern manufacturers don't bother giving out the windows disks anymore- it's cheaper to just partition the hard drive and make one of them recovery. Unforunately if you kill your hard drive then you're out of luck.
After that, the reason I am happily staying with windows is because the UI and how things work. Gnome 3 is one sexy beast, and it works well. I also like razor qt and lxde- both remind me of windows, but redone for speed. both are fairly aesthetically pleasing as well.
Pretty much tied with number 2 is is security. When I used windows I was decently careful, and I got a single virus within several months, if at all. Usually I took it down before it did anything. However, for secure purchases, etc I would always use my phone. Since I was flashing a ton of roms and only restoring necessary apps, I didn't really have to worry about viruses after each wipe. Now with linux (ubuntu 12.10 x64 and soon to be openSUSE or chromeOS dual boot) I have less fears. Many features are already packed in, so I don't have to install so many applications to get things done like with windows. For those I do install, I have much more control over.
finally 4, which is somewhat farther behind. I support open source, I believe in it as a way to go. Using a linux PC only reinforces this.