The main reasons why I bought a Nokia Lumia 1520:
1) I had few phones in my life, but almost all of them were Nokia (like N73, N82). I loved a lot the phones at that time (6-8 years ago), especially the camera on N82. So Nokia captured my attention.
2) The main reason I didn't want Android is because of Google. I don't like the companies, who's main revenue comes from marketing and ads (like Google, FB). I understand that the main reason of ads are keeping people informed with different offers, products etc. At the same time, THE SAME companies have the biggest share in their businesses (Facebook in Social networking, Google in Mobile OS, browser, search engine), so it's very unlikely that these companies will keep improving (in all of the aspects) because they don't feel the competition. Therefore, it's very likely that companies like MS (in this case, has a lower mobile OS share) will do their best to provide awesome products, services and support.
3) The main reason I didn't want iPhone is because I don't like the Apple ecosystem (Mac OS, iOS, iTunes, etc). The only 2 Apple products that I used, is and old iPod (don't know what gen, with 2GB memory I guess) and iPhone 4 (I got it from my sister, since she bought a new 5S and I needed a phone because my old N82 was almost vanished). All of my life I used to use Windows, and I was very satisfied. I didn't find any reason to use the Apple desktop OS so far.