I wear somewhat expensive wool socks in the winter but then in the summer when working outside I wear those cheap white tube socks you buy in a package.
For me my most useful clothes are a couple jackets. One is an LL Bean Goretex shell type jacket with hood. It sheds rain so as to keep me dry and because the wind doesn’t penetrate it, it will keep me warm down into the 30’s despite only being a thin shell. If I am walking at a decent pace or riding a bike it’ll keep me warm down into the 20’s. Of course I am mostly impervious to cold so your mileage may vary. For cold weather what I find incredibly useful is a Carhartt winter weight jacket with detachable hood (that I always just leave attached). Those Carhartts never wear out and mine has always kept me warm no matter how low the temperature has gone.