I'm often asked why I have a Windows Phone when people see my HTC One M8. The answer is simple - it works for me. It provides everything I want, and the features I expect. There are some UI elements that take some getting used to, but in the end it's just a UI. I simply learn how to use the UI, and move on. If someone plopped you down in front of a Linux desktop and asked you to install a printer, it'd probably take you some time to figure it out. It's the same for any OS.
Here are some of my thoughts on the OSs:
iOS - It's the "gold standard" in America (not the World). However, I feel I cannot interact with the system the way I want to. I'm forced to use iTunes for most basic things, such as adding my MP3 collection, movies, ringtones, etc. I cannot simply connect the phone to a PC and drag the files over. I'm also amazed that through 9 major revisions to iOS, I can't attach a file to an e-mail. Heck, I can't access the file system at all. I can't save an attachment to a folder structure I'd like, nor find the file later and attach it. Sure I can put the file in Dropbox or some other cloud storage, but then I cannot attach multiples to a single e-mail - just one at a time.
Android - This OS gives me the freedom to do almost anything I'd like. However, it's highly fragmented and American carriers tend to abandon the phone quickly after releasing it. I was always feeling left out when Google announced the cool new version, but I was 2 versions back because Verizon or AT&T wouldn't release the update. The solution here is to go Nexus, which was a great idea, but poorly executed - with Verizon still controlling updates.
Windows 10 Mobile - This is somewhere between the complete freedom of Android, and the locked experience of iOS. I can change some elements of the UI to personalize it, but I cannot reskin it completely. However, it's a familiar interface, having Windows 10 on my work PC and home PC/tablet. I don't have to remember a different way to so something on the phone vs the desktop. There is a folder structure that I can save my files to - and I can connect my phone to a PC and copy over music, movies and ringtones easily without software. I can attach files to e-mails, and save attachments in the structure I want. Cortana works well for me, and reminds me of the experience I had with Google Now. I love when she tells me it's time to go home.
To sum up - Windows 10 Mobile works for me. It may not work for others, but that's not important to me. I don't understand the hate. "iOS is the only OS that works - all other mobile OSs are stupid!" "I can't believe you use anything other than Android!". How about, "iOS works for me and does what I need a phone to do." or "I need freedom on my phone to do whatever I want, so Android works for me."
Thanks for reading my post - I'll go back to cleaning up all the testosterone that's being hosed onto the walls around here.