I'll tell you how I've landed on a Windows Phone -- one that I paid for out of pocket, and using a plan that I also pay for out of pocket.
(I mention this only because I'm an MS employee, and I want to avoid the problem of someone claiming that I am astroturfing here)
For the last year or two, I had been using a used iPhone 3G. I had to jailbreak it so I could SIM unlock it.
I never bought any apps from any appstores. Free apps, yes. Paid apps - no.
The basic problem with the iPhone series is that apple simply obsoletes its hardware too quickly. Most of the apps in the apple app store couldn't install on my phone, because my phone couldn't be updated to the newest OS. The phone was unbearably slow when browsing desktop-class pages.
I feel like apple is a premium-price for a below-average experience.
Regarding Android - every android phone I've seen has been completely different from the others. If I pick up an android phone, it always takes me a while to adjust to the quirks of that particular handset's UI. I'm attracted to the ease of "owning" an android device, but, ultimately, I want a phone that just works. I rarely want to tinker with it.
Finally, Android bothers me because I don't use gmail and I don't trust google. The people I've talked to claim that it is difficult to really make the most of an Android phone without giving your life over to your google account.
So, Microsoft finally comes out with the Lumia 521 -- a no-contract phone that is natively built for Windows Mobile 8. I really like this phone. It has a fast browser, and the 1st party apps are quite good. It is like $120 from Wal-Mart. The camera and photostitching apps are good, and it comes with a built-in Nokia mapping/navigation program that has complete offline capability. This is important for me since I don't have a data plan and I am often in places with no data service anyhow. The Nokia HERE DRIVE and HERE MAPS applications are fantastic.
The windows mobile UI is great. More consistent then Android, and better information density than iPhone.