Ever since receiving a pair of Fitsok in a marathon gift-bag (10 years ago), I've worn them exclusively.  They're durable, breathable, and seem to prevent hot spots when I'm switching shoe styles.  In the cold, snowy winter of Minnesota, I wear a 1/4 length Fitsok underneath a crew-length Fitsok and have perfectly warm feet while running down to the -20F range.  (Yes, some of us are partially insane and go running at those cold temperatures.)  The attributes that make them good for running also make them good for hiking & camping, though I will use wool socks with boots when camping in the dead of winter.