For me the decision revolved around how I use my iPhone. I view a lot of photography on mine when I'm out and about, so I wanted the largest screen size for viewing images, of which the majority are in the 4:3 format. So, the 8+ was the logical choice for me. It has the exact same wide gamut colour display of the X and I've never been able to see the pixels on any of the previous iPhone+'s. Those that claim they can must have amazing eyesight as I have 20/20 vision! 
I did momentarily consider jumping ship to the Samsung S8, but when I went in and tested it out with some of my own photographs on a micro SD card, I found it oversaturated every image!
I did momentarily consider jumping ship to the Samsung S8, but when I went in and tested it out with some of my own photographs on a micro SD card, I found it oversaturated every image!