Proportionally higher WP users than the general population. Not surprising as I'd think a relatively high proportion of Xbox owners would be WP users.

iOS low, and Android about the same as the general population.

I'm guessing PS owners tend towards Android. But I wonder what Wii(U) / (3)DS owners favour?

I currently have Android.

Nothing against iOS, but I already used it for long and I figured I had to try something new.

I love Android. I will probably stick with it for a while.

I chose Windows Phone 8 to be different from the Droid and iStuff crowd.
That's pretty much it.
And I honestly couldn't be happier with my Lumia.

iOS. I was given the iphone for free.

Would prefer to switch to Android.

Android.

Was a cheap one. Got it for my birthday. Seems to work nicely.

iPhone, I've had the original and 4S. I am staying with iOS because of the 3rd party developer support and I don't see anything in the competitor's offerings that I want. Customisability in phones are too much of a hassle, it's not a PC why should they bother me with tons of options. I've jailbreaked my first iPhone back before the App Store opened and frankly it's a bit of a chore to mix and match features, right now they've designed their UI just right and everything I need to do can be done with a swipe or a tap and a bit of a type. I don't see any need to change the desktop layout, frankly if I have to think to make a phone work then the design has failed. Smart phones should be easier to use than dumb phones, not the other way around.

Android - Like it for its customization.

I use Android (smartphone and tablet, last one is a N7 with 4.4) and now Blackberry 10 too and I enjoying it a lot. I previously had a Windows Phone, still the 7 (used Mango and Tango versions), it was fun to use too.

Android is my main OS, since it is more feature filled and I like the UI (the AOSP one on Nexus devices and, thanks god, newer Motorola ones). But I like to have a second phone with a different OS (I have 2 numbers and it's much better to have 2 smart phones so one stays with my secondary number and connected to 3G and the other with my main number and no 3G so it can got a few days of use without charging).

Have a Lumia 920 for about a year now. Used to have an iPhone 3GS for 2 years. I like the Windows iOS more but I must admit I don't bother with apps on my phone. I use it purely for music, videos, web browsing and editing work documents in Office Suite.