Merino wool is the most popular choice for ski base layers for good reason. Its biggest advantage is natural odor resistance—you can wear it for multiple days on a ski trip without it smelling, which synthetics simply can't match. It also regulates temperature beautifully, keeping you warm on cold lift rides but not overheating when you're working hard on the slopes.
Another key benefit: merino stays warm even when damp from sweat, whereas synthetic fabrics can feel clammy against your skin. This matters a lot during those transitions between high-output skiing and sitting still on the chairlift.
The trade-offs? Merino is less durable than synthetic options and requires gentler washing—no hot water or high-heat drying, or it'll shrink. It's also typically pricier. But if you're doing multi-day trips or all-day resort skiing, the comfort and odor control usually make it well worth the investment.