After using the Nokia Lumia 520/521 and then Lumia 635, I got the Microsoft Lumia 640. It is a major improvement in many areas and I am shocked to see how good it is at a price several times lower than an iPhone or Samsung S6.
For starters, it supports LTE, came with T-Mobile's WiFi calling, supports VoLTE, has an excellent battery life, full 720p 5-inch screen, has both the front and the rear cameras, a flash for the main camera (8-Megapixel resolution), has a 4-core processor and 1 GB of RAM.
The phone has 8 GB of storage and supports MicroSD of any size ( I got the 32GB MicroSD). And all of this costs less than $100 now. Wow.
My T-Mobile phone came with Windows 8.1 Denim and Microsoft stated this phone would be among the first to get Windows 10. It feels solid and convenient in your hand despite its large 5-inch screen size.
It even came with 1 year of free Office 365 online, which is normally $70. Not that I am using the actual office part of it, but it gives you 1TB of cloud storage.
I have had the phone for about 4 months now and it has been super-stable and responsive. And although there is a lack of second-tier apps and some of the apps it has are unpolished comparing to the iOS/iPhone counterparts and although the Waze app for Windows Phone is no longer supported and keeps crashing, the Lumia 640 is still inexpensive and awesome.
I have dropped the phone several times and so did my wife. In each case, the phone developed small dents that do not affect the functionality. In a few instances the case opened and the battery fell out, but I put it all back together and all still works. Try this with your fragile iPhone!
The battery life is simply amazing. Easily enough for a full day of heavy use.