I mainly wonder about the BIA 5 leg. It's probably offered because it's slightly shorter. Remember mapping programs chose based on time (or distance).
This area is flat, so the main question is road quality. Streetview fo BIA 5 is incomplete and old (2008), but Streeview from the NM371 intersection, and the Sat view shows an upgraded road with normal lane markings.
371 passes through a heavily irrigated area just north of that junction, which suggests increased traffic and access in the last decade. There aren't many towns.
If I drag that route up to Shiprock, US64, the time/distance difference is negligle.
North of 64, 550 further east is 4 lane up to Durango, while 140/141 is just two, but terrain looks similar.
You don't hit mountain driving until after Durango.