Depends on the climate some. Here, it tends to be hot and humid, even fairly often in the hills and mountains to some extent (mid central East Coast of US, south of Maxon Dixon line). When hiking here, I try to wear the coolest sock-shoe combo I can (sometimes sandals or those hybrid shoe-sandals, both with socks), when rarely doing summer hikes (my hiking season is primarily from mid fall to early spring, unless going to a different, cooler and/or drier climes for a trip).
For socks, that is often a thin, but not sheerly so, flax-linen with as much synthetic blend as I can find. So far, the highest synthetic to linen blend I’ve seen, is a 12% nylon and 2% spandex to 86% linen blend. These have been some of the coolest (and lowest odor and fairly quickly drying) socks I’ve found.
Thin nylon socks with copper are ok, but do not wick as well as the above, and tend to be too tight because they are often sold for “compression” (so I always get a larger size than what is recommended for my shoe size). They last longer and dry a bit quicker though. I like tencel-nylon/nylon-tencel blends in certain ratios, but they are hard to find in the blend ratios I like (from about half and half, to as low as 30% tencel).
If in a cooler and/or drier climate, I would be ok with a thinnish, about half merino wool half nylon or so sock. That’s what we primarily used on the CT.
Agree with some others, fit is important. Don’t want too tight nor too loose.
Way before I knew about BPL,and also before I put a lot of thought or analysis into backpacking stuff, I did some fairly stupid/illogical (in hindsight) things. For an example, we hiked the Camino in Spain about a decade ago. I don’t know what I was thinking, but for some reason, I decided to go with a pair of stout, Ecco, Gtx lined hiking shoes, and some medium thick wool socks. The saving grace is that I also brought some hiking sandals.
I would wear the shoes first thing in the morning till Siesta time, then during same, I would take off the shoes and socks, turn the socks inside out, let them and my feet dry, then once ready to hike again, don the socks and hiking sandals for the rest of the day. In hindsight, I didn’t need the Gtx shoes at all.
The odd thing was that I was the only one that I knew of that didn’t get any blisters the whole time (blisters often were talked about at some point). And silly as it was bringing those Gtx shoes– I distinctly remember seeing a number of Germans wearing full on boots–some of which were those very high military like boots.
While feet are pretty individual, some things just aren’t all that holistically logical and wouldn’t work well for most, most of the time, like Gtx lined shoes or heavy duty, high boots in summer.
P.S. If I was hiking in a desert/highly arid climate during warmer seasons, I would go with a combo of light colored mesh shoes and medium thickness, primarily cotton-spandex blend socks (ok if there is a little nylon or polyester for durability). When I’ve been in those climes, I’ve found that I actually prefer clothes and fabrics that hold onto moisture as much as possible to extend the evaporative cooling effect. Things dry too fast in those climes. Except for shoes, I don’t wear anything that contains a lot synthetics or wool at all when in those climes, but primarily linen-cotton and high cotton-other blends. Cotton with a fair amount of spandex blended in (10%+), seems to hold onto moisture the most/longest.
Cotton saves when it’s consistently hot and very dry!
