35, 50
In 35mm, perhaps the distance between observational and participatory imaging is fifteen millimeters.
Seeing Layers
The 50mm lens is more front-to-back than side-to-side and compresses things together, perfect for layering foregrounds over backgrounds.
35 is a lonesome focal length
A 35mm pushes backgrounds away and magnifies foregrounds.
The Rule of Thirds
View something, then around and past it.
Compression and Separation
Lens selection is a creative choice made before stepping outside. A 50mm is how a photographer sees; a 35mm is how one thinks, and a 135mm is how one sees and things while driving.