Before WP7, I was an Android hardcore user. I never stopped flashing ROMs, scripts, features, mods, and building my own OS too, and customizing my Android phone as I like it to be. That's why I switched to Android from WM6.
When WP7 finally came out, I really didn't like its UI (like any other Android user), because it looked a bit old. But the performances were really amazing... I wondered how a cheap WP7 phone with old specs could beat a top-notch Android smartphone in terms of performance and smoothness. And simplicity, of course.
There were a couple of features that caught my eye, too. Live Tiles, clean, simple and intuitive UI, deep Windows integration, and developing tools. So I decided to make the right move when Microsoft announced its partnership with Nokia, and got a Lumia 800. I really loved (and still loving) that phone. It doesn't have as many apps as Android, but I'd choose quality over quantity.
I decided to give up on Android and switched to Windows Phone definitively. Now I'm enjoying my 8X. I still have my Galaxy Lag 2, btw.
(I never liked Apple products because of lack of innovation and Apple limitations).