I can vouch for SmartWool as far as their running socks go. I own at least a dozen pair. I can only imagine their boot socks would be of the same superior quality. If you do choose SmartWool, check out backcountrydotcom. They offer a pretty deep mil discount.
A note for aspiring, younger, or soon-to-be military members. Whether you are in SOF or not, there are certain things that you cannot and should not go cheap on. Socks is one, boots another, quality running shoes another. Dropping over $10 on a pair of socks may hurt but your feet will be happier after many miles of carrying you. It is entirely possibly to go through selection or qualification courses events with zero blisters or foot problems if you have quality socks and boots. Find what works, save the money, and drop the coin. It's a small part of the entire process but you'll be surprised how broken and miserable you feel if you get blisters and hot spots caused by cheap equipment.