Over the years, I've collected quite a few Icebreaker pieces. While not cheap, they are durable and really versatile, and always made of high quality merino wool. Merino wool, in my opinion, is the perfect fabric for cycling. It is soft and comfortable (not itchy in the least!) it wicks moisture well, breathes well, and performs well when wet. It doesn't get stinky the way synthetics do, so you can ride in it and then go straight to the office, bar, dinner party, grocery store, etc, without having to change out of your cycling gear. Simple!
While there are many companies making merino clothes, I value Icebreaker's strong environmental, manufacturing and animal welfare ethics. They have a very transparent supply chain - you can even trace your garment's "baacode" (ha ha!) back to the farm in New Zealand from which its wool originated.
This sheep looks like it has a pretty fantastic life, don't you think?