The best materials for running apparel are those that provide comfort, durability, and flexibility. Common choices include polyester and nylon, which are lightweight and moisture-wicking. Merino wool is another great option for colder weather due to its excellent thermal regulation and moisture management. Look for fabrics that also have a bit of spandex or elastane blended in, as this adds stretch and improves fit. Ultimately, the best material will depend on climate, personal preference, and the type of running activities.