For longer flights, I tend to use Physix gear compression socks. Their moderate compression is perfect for flying, they still have a fashionable look (since they also come in many colors), they are durable and comfortable, and, best of all, they don’t break the bank. As someone who has a leg condition (my Achilles tendon is short), it is more important to feel comfortable on long-haul flights because otherwise I tend to experience serious leg cramps and pain.