It seems that we’ve hit a wall when it comes to mobile screen resolutions - not that the technology isn’t there, it’s the purpose that is missing. Sure, VR enthusiasts (15% of voters) are excited for 4K 2160p screens since virtual reality headsets need all the pixels they can get.
However, as some of you rightfully pointed out, Sony has no interest in mobile VR since it will compete with the PlayStation VR. Samsung has no such qualms and works with Oculus (both on the Rift and Gear VR) and seems to be working on a standalone headset. Asus and others are allegedly working on standalone solutions too, so there won’t be much point to taxing the chipset and battery with a 4K screen, just for some VR play.
The sweet spot is definitely 1080p - about half of voters chose that option. That is related to screen size, 5.5” seems to be the most popular option and QHD is borderline making any sense there. The higher resolution still has fans (around a third of voters), no surprise given that 6” phones are becoming more common.
Finally, very few picked 720p, mostly people who want 5” or less of screen. Now that many phones have the option to lower the resolution in software, you can have the best of both worlds - 720p for performance and battery life when you need it and a sharp screen the rest of the time.