Nickel-chrome is recommended for auto emblems due to its ability to maintain shine and resist dulling when exposed to the elements, with costs around $10 per piece for chroming. German silver, which contains no actual silver, is also suggested for its durability, although it may peel if edges are exposed. Stainless steel, particularly high-grade options like AL-6XN and 254SMO, are noted for their resistance to oxidation in moist environments. The discussion emphasizes the importance of considering environmental factors, such as pH and chloride content, which can affect metal performance. Ultimately, selecting the right material depends on the specific conditions the emblems will face.