I don't buy the argument that synthetics are all hype and marketing. Synthetics are the proven winner for the self-propelled traveller who doesn't have the option to jump in a truck and dry out. They're also good value because they last and last.

That said, cotton thermals have their place. The waffle weave seems to dissipate moisture better than jeans or T-shirts.

There's a cotton/wool hybrid made by Stanfields that I wear in very cold weather. It has a onionskin thin poly/cotton layer bonded to medium-weight wool, and it's very comfortable to wear.

But these days I basically live in synthetics, and see no reason to go back.