breathability is the key criteria for clothing. Polyester and synthetic fabrics are nearly all terrible at this compared to natural fibres.

Natural fibers cannot be grouped together in this way because there is a huge variation.

This is where cotton fails and synthetic microfibers come out ahead. Cotton retains water, swells when wet, and suffocates as water tension spans the threads that are thickened by the swelling. Synthetic microfibers wick moisture away, and do not swell when wet, which gives excellent breathability. Cotton is fine as long as you don’t sweat. Or exceptionally, if it’s extremely hot in some windy situations the water retention can be a plus. I used to don cotton and hose myself down before getting on a motorcycle on a hot dry day. The evaporative cooling effect worked wonders with the high relative wind. But outside of that niche, such as sports, microfibers are king which is why sporting goods shops fetch high prices for high tech synthetics. As someone who sweats profusely more than normal, cotton is a non-starter in warm climates. Evaporation from soggy cotton simply cannot keep up with the rate that I add sweat. So a cotton t-shirt gets soaked in sweat and remains wet the whole workout session, and for days thereafter.

I used to wear tighty whities which made my gear sweat. Switched to Pategonia boxers and wow what a difference in breathability.

Wool and synthetics are similar w.r.t. comfort hence the term “smart wool”. But indeed natural wool is pricey and non-vegan.