A classic crew neck in a grounded color like blue or grey offers the broadest use. It layers cleanly under blazers, long coats, and technical outerwear, and it looks intentional with everything from tailored trousers to relaxed chinos. If you already own several crews, a mock neck zip in a neutral shade adds a different neckline without feeling trend-led. Choose the weight that matches your climate and how often you layer coats or jackets.