I almost exclusively wear cashmere in winter because it's naturally more insulating than most organic textiles. Granted, it takes a lot of effort to spin, dye, and knit cashmere goat wool into one ...
Few items in a guy's wardrobe feel as effortlessly elevated as a cashmere sweater. No shade to wool, of course—a chunky cable-knit or fine merino turtleneck are essential in their own right.