I can't use iOS or Android because they are missing key apps and functionality
IOS and Android are missing key features and apps that are widely available on Windows Phone. As nice as the hardware looks I don't think I could give up these things I find absolutely necessary for my day to day work.
Office apps that don't blow up my formatting and that sync with my skydrive and office 365 share point servers
Notifications that make sense. The simple icon based launchers mean that those other OSes need an extra inbox of inboxes that don't let me filter updates for specific things I'm interested in.
No Xbox live integration. Have you seen iOS's game center? Totally lame. I want to show my buddies how I finally found all the skyrim shouts on my 360 right on my phone...
Pinned shortcuts to specific notes from Evernote and OneNote. I use these apps to keep little reminds of the chords used in the songs I'm practicing and then I just pin the songs for the set of the day to my home screen. No such functionality exists on these other platforms. How Apple and Google think they can continue to compete with icon only interfaces is astounding to me.
Speaking of pinning, why does apple force me to open iBooks to get to my books... Totally douchey branding move. On my windows phone I just pin my current book to the home screen and it's right there with the cover showing and everything. Ditto for audio books, streaming radio stations, etc.
And how about some social networking sanity. I care about the posts of my wife, whatever network she's posting to. One pin and boom, everything in one place. Joe so and so's latest cow purchase in friends with mafias doesn't get the same priority or feed space. Can I control the social story on a person basis and not a network basis on iOS or Android? I don't think you can, but I'd be happy to be told otherwise.