It depends on the work cb. If strenuous I go light or mid weight base layers . If sedentary I go mid to heavy weight. It all depends on the conditions , activity level, duration of such and personal biological factors. First …. NO COTTON as a base . I’ve had good experiences with cabelas and bass pro shops stuff and under armor. Any one of your choosing that wicks moisture away from skin to the mid or outer layer. Base layers that don’t wick will keep you cold , so no cotton , I repeat NO COTTON base layers. Overdressing is no good either. The idea is enough clothes with a wicking base layer without sweating too much . It won’t matter how good the base layer is if your wet . I walk a lot to my hunting and fishing locations and will often walk in just the base layers , bb cap , and boots . When I get where I’m going only my feet are damp sometimes from sweat so off those socks come and néw ones go on . I’ll cool down a bit if a little sweaty but before a chill sets in and then put on my outer layers. So it’s the same for feet. With base layers dampness and sweat are your enemy. If you’re wet you’ll never be warm . It took a lot of trial and error over the years( everyone is different) to figure out how to dress properly for most conditions. It actually is a science .