My recommendation would depend on what you plan on wearing for footwear. I wear an 8" insulated boot. Whatever sock you get, make sure the fit is not tight inside your boot, or your feel will freeze. The merino wool that others have suggested is usually thin enough to leave some necessary space. I have these ones:

https://www.trekbikes.com/us/en_US/a...-sock/p/11724/

Any of the warmer ones from Wigwam, like the Nomad model https://workingperson.com/wigwam-soc...52-103355.html, I have the Nomad, and it is excellent.

or from Wright like the Merino Trail Crew https://www.socksaddict.com/wrightso...ail-crew-socks should work well if you have high-top, insulated boots to go over them. I have not used this model from Wright.