28mm equivalent or therabouts (this is a bit wider than 28mm) is my favorite focal length across all systems.
A 28mm, compared to 35mm allows you capture the environment = perfect for storytelling or interesting city scenes. Particularly in interesting cities like Paris, London, etc. that focal length comes into its own. On a MF sensor also the longer focal length for 28mm does not distort people or objects too much, even if not too far away - ie, it is also good for enivornmental portraiture.
Anything below that and you are in UWA territory and then proportions, perspective become more important to get a nice shot. The 24mm is perfect for architecture, but for city shots requires heightened focus on composition and therefore quite a bit of skill. You can see that very well with Alan Schaller's work with that focal length - he is an absolute master of composition.
I think also on phones the 28mm FoV equivalent is a widespread main camera setting - ie because of the flexibility. Also let's not forget that Leica built a whole camera line initially on 28mm - the Q series ...
I hope for the Leica M the next thing they'll do will be a 28mm APO Summicron with perfect IQ across the frame - this would be the ultimate documentary city kit for me (sometimes a smaller camera is preferable in cities).
Great shots and should I ever get an X camera probably the first lens!
