My priority are roads where I can safely and easily control the lane, while motorists can easily pass, which for me means low stress. I have 2 viable routes I can take to work, within 1 mile of each other in length. But the 1 mile longer route is far easier: less traffic, less hills, less stress. So I go that way. The shortest route (the way I drive) I do not consider viable because it involves several miles of 2-lane no shoulder 55 MPH state highway with very high traffic volume. So I don't even consider cycling that way.