I’ve tried oodles of base layers and nothing makes me feel better or warmer than my Capilene baselayer shirts and pants. They are an excellent wicking base layer for many different activities including backpacking and whitewater kayaking.
I’ve hijacked the Patagonia graphic (above) that best explains which fabric thickness is best for different activities. It is a very good guide for understanding the relationship between activity levels, outdoor temperatures, and base layer thickness.
I use a Capilene 1 long sleeve jersey and long underwear pants in mid-spring, summer and early fall. The fabric feels extremely silky and helps keep my sleeping bag free of sweat and body odor. In early spring and late fall, I switch to a Capilene 3 jersey and long underwear pants for extra warmth. This sleeping layer can be used as a warmer backup to my daytime base layer or if my daytime base layer gets wet.
The weight of the of a Capilene 1 crew jersey (size xl) is 5.8 oz and the weight of the long underwear is 5.9 oz. Both of these garments get packed in the stuff sack used to hold my sleeping bag. The weight of my Capilene 3 crew jersey (size xl) is 8.1 oz and the weight of the long underwear is 7.5 oz.
Over 50% of every Capilene garment is made using recycled polyester and Patagonia will accept used clothing for recycling. Of course, you have to destroy it first, and that seems unlikely. These clothes last and last.
Disclosure: The author owns this product and purchased it using their own funds.