35mm.
This poll appears not to be limited to RF cameras, so ...
In 135 format, I shoot old SLRS and my least favorite focal length is 35mm.
(My favorite focal lengths are 28mm and 85mm, with honorable mention going to 50mm. I normally jump from 28mm to 50mm, with no need for anything in between.)
For travel and living abroad, I have used compact, fixed-lens RF cameras (Olympus 35 RC and Canonet GIII 17 QL), and the 40 - 42mm focal length suited me fine for these purposes. This is close to 35mm, but the latter still seems a bit wide for what is passing for a normal lens.
In medium format, which I shoot more and more, my lens selections are more limited and I haven't had a focal length that I didn't like.
- Murray