For the money it's hard to beat Duofold.
Unfortunately, Duofold changed the men's bottoms and eliminated the fly so the last couple of bottoms that I've bought are Ice Breakers, which are 100% merino wool.....but I don't think they're as warm as the Duofolds which are heavier and a 40% wool blend. The Ice Breakers are more expensive. I still buy the Duofold tops, but not the bottoms.
Hot Chili's are very popular as well, and don't over look the Smart Wool brand either.
For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places.