Comfortable and breathable
Merino wool has sort of taken over the travel and hiking space these days.
Its claim to fame is "moisture wicking". This means it moves moisture away from the skin, so it can evaporate and prohibit bacterial growth. The socks don't smell or feel weird to wear for a couple days in a row.
This also makes it great for long flights. I've had issues with other socks making my feet feel itchy on a long enough trip. No issues with these!
Darn Tough is a pretty good brand for these as they use a decently high percentage of merino wool in their products, but they're not the only company in this space. $20 may feel like a lot for a single pair of socks, but it's worth it!