I'm from South Africa and upgrade my phone (on contract) every 2 years. I've had:
HTC Trophy (WP7)
Nokia Lumia 920 (WP8.1)
Microsoft Lumia 950XL (W10M)
I'm not going to lie, a bit disillusioned with Windows Mobile. I've had quite a few bugs since I got the phone (3rd Feb 2016). Quick updates are really good though, feels like progress is being made. I fixed one of the most annoying 'bugs' yesterday. Turns out they added in a 'Prevent accidental camera launch' option which ended up disabling the camera button about 50% of the time when I needed it. Glad I figured that out as it was annoying as hell.
I really hope they keep working on the UI/UX. As a Web Developer (mostly front end design/development), it really irks me just how inconsistent the usability and design of Windows 10 is overall. There are so many things they can improve on. Android 6 and iOS9 are miles ahead in the design of the OS (UI) and a step or two ahead in UX (usability).
Here's hoping they keep improving.