We all have smartphones. Billions of people use them and they produce more greenhouse gases than any other consumer electronic device, furthermore they require irreplaceable rare earth materials that are gained in terrible conditions. 

In Europe you can buy a Fairphone. Wikipedia summarizes their endeavor in the following way:

Fairphone is a Dutch electronics manufacturer that designs and produces smartphones with the goal of having a lower environmental footprint and better social impact than is common in the industry. In particular, the company aims to minimize the use of conflict minerals in its devices, maintain fair labor conditions for its workforce and suppliers, and allow users to maintain their own devices.

This sounds amazing, but the device is bulky and the hardware is relatively expensive. I can buy a superior refurbished iPhone for half the price. I'm asking specifically for an iPhone over an Android device, because they tend to have longer software support and therefor theoretically you can use them for longer.

 My questions are the following: 

• Is it better to buy a Fairphone or to buy a refurbished iPhone? 
• Or should I not worry about this question at all, because the impact is insignificant compared to donating money or labor?