Here are the fixed lens 35mm film cameras that I use in one-lens/one-camera situations:
Minolta Hi-Matic 9 rangefinder with 45mm f/1.7
Canon Canonet QL17 G-III rangefinder with 40mm f/1.7
Canon Sure Shot compact with 38mm f/2.8
Nikon L35 AF #2 with 35mm f/2.8
GoPhoto Aqua Pix Underwater Camera with 30mm lens
Mazda/Vivitar P&S camera with 27mm lens
50mm for 35mm cameras; 80mm for 6x6 on the Hasselblad, 135mm for 4"x5", but that is just the starting point. The composition dictates the focal length - distance and perspective.
On my Hasselblad, the 60mm F3.5. If I want longer I use the 120mm lens. These are the only two lenses I actually need. Any thing else is a special situation. But I'm soon taking a trip taking only my 38mm SWC.
with 35mm cameras? 50mm, 70% of the time. I don't really like wide much for 35mm cameras. I have wides, I just don't use them much. Probably my second favorite is 85mm to get a little more narrow.