List of all iPhones, from best to worst based on my opinion:
4s - The pinnacle of Apple's designs
2g - The one that changed everything
4 - Nice design, but not quite the 4s
SE - Perfect size, good performance and battery, all for a low price
5s - Touch ID
5 - Very light weight, but a step down in design
6 - Hated the rounded edges, and looked like an Android phone when I first saw it
8 - The glass back made a slight improvement over an already boring design, but still a 6sss or 6s^3
6s - Not much of an improvement over the 6
7 - One of the saddest iPhone releases, it was basically a 6ss or 6s^2
X - Probably the best balance between the large size screen vs size of phone, but too expensive
Xs - Slight improvements over the X, but still too expensive
3G - too much plastic and a downgrade on design from the 2G
3GS - No big improvements over the 3G while still having the all plastic design
6s Plus - Same as the 6 Plus, but the bending protection improved
6 Plus - Too big, hated the rounded edges, and looked like an Android phone, plus it would bend too easily
8 Plus - Too Big, the glass back made a slight improvement on design, but still a 6sss or 6s^3
7 Plus - Same issues and design of the 6s Plus
XR - Too Big and thick, all the issues of the 6 Plus with little improvements and for more money
5c - Plastic kid's toy
Xs Max - Too big, way too expensive, the high end cost more than Macs that I have purchased, and I would get much more use for a longer time with a Mac than this iPhone