Most “experts” seem to agree that crimping is best for automotive application. Since I’m not one of them, I can’t really say.
PROS
Accessibility, simplicity and affordability are the biggest advantages of soldering. Solder and flux are the only materials needed for soldering, and tooling is minimal (a soldering iron, assorted tips, and fixturing if necessary). A basic soldering kit can be used to perform most soldering applications. For more delicate, low-current applications, such as circuit boards in consumer electronics, soldering is a reliable method to join conductive materials and terminate contacts that are already mounted in a connector.
CONS
More labor-intensive and time-consuming than crimping, soldering also has a greater risk of its connections succumbing to mechanical or temperature stresses. This makes soldering a less practical option for harsh environments where corrosion, repetitive movement and vibration can cause wires to stiffen and the filler metal to degrade over time, leading to electrical failure. If the heat generated during the soldering process is not controlled properly, problems can arise including damage to your components when wire, contact or connector thermal limits are exceeded. Meanwhile, if the solder does not completely melt, the “cold solder” joint can produce a rough, inconsistent surface, resulting in a weak bond.