I bought Coolmesh Merino socks to wear with my paddock boots. Tall enough for the boot, comfortable foot. Perfect for what I bought them for.
However, if someone is using them for walking, I'd recommended the Coolmesh ll non-wool socks which are lighter weight and keep your feet cooler.
Wrightsocks are the best! The double layer is both a great insulation as well askeeping my feet dry.