Security, Privacy and Platform Consistency on Android. Yes to the first and the last because of the millions of phones stuck forever on the many older versions of Android. But aren't there also quite a number of people stuck on older versions of Windows phones too? I also know a few iPhone users who lament the way their older handsets struggle with updates to these. Privacy maybe the same on those old versions too. But even on most of the cheap new android phones privacy is easily managed from the Application Manager/App Permissions in Settings.
I have to use my Android phone as my main phone because my L830 simply isn't reliable enough. Example, the .1944 update received yesterday put the phone into boot loop for a couple of hours before I could get it to run and install it. And while typing this post the screen has blacked out and frozen 4 times.
Even so, it's my favorite ever phone and I'll use it for as long as struggles on.