I made up a phrase in a topic yesterday
>link here< referring to field of view not by the angle claimed by the manufacturer (which often isn't true) but width of the field of view relative to other cams, which I called rFOV.
The interesting thing about angles is that it's not a linear relationship. A diagonal ~160 degrees translates to a horizontal angle of 140'. But 140' isn't giving an image 1.4x the width of a horizontal angle of 100' - it's actually approximately 2x the width of view.
Similarly, 130' horizontal is 1.25x the width of 120' horizontal.
140' horizontal is 1.3x the width of 130' horizontal.
Anyway......back on topic:
For a single front cam I would choose medium angle (~130' diagonal, rFOV = 8) although angle isn't the only factor when choosing a dashcam.
That 130' diagonal gives a more realistic perception of speed and distance to a random watcher of the video.
Too wide angle or too narrow angle and the camera creates an optical illusion that you were either taking too long to stop or you were following the vehicle in front too closely.
For a rear cam I would choose medium or wide angle because details are easier to capture on cars approaching from behind due to their relatively slower approach speed. Wide angle creating a bit of an optical illusion regarding stopping distances is not a problem when it's rear-facing because it's not your stopping distance being called into question.
Given the luxury of having two front cams (which I advocate on ground of the numerous potential reliability issues) then it is possible to have both a wide and a narrow angle cam to give the best of both: one has a wider field of view and the other has a zoomed-in image.