Smartwool for 20+ years never let me down once, and last a long long time. BUT, Cabela's also sells some great merino wool socks. Bought some Cabelas USA made merino wool synthetic blend extreme cold weather socks for my sons and I for last deer season and my sons LOVED them as for some reason that escapes me their feet get colder much more easily than mine. These Cabelas extreme cold weather socks were the thickest socks I've ever seen. My boys wore them in some all leather 200 grm thinsilate Bellville USGI ICW WP combat boots and their feet remained toasty warm in temps down to the teens while sitting in ladder stands for 4-5hrs at a stretch. I wore them in the same boots recently scouting some new private deer land I got and spent two days over 6 hours each day on my feet walking and scouting the land, putting up trail cams and taking notes and marking aerial photos with all the deer sign I found and my feet were plenty warm and very comfortable both days. The temps for those two days were never above the teens and the WC was at or below zero, in the early hours just after sun up the WC was around 12-15 below zero and my feet never even approached getting cold.
You can not go wrong buying Smartwool.