This is one I can’t easily answer. I have absolutely no preference when it comes to fiber content, weight, color, pattern, brand, etc. I don’t like scratchy yarn, I don’t care for linen, but when it comes to choosing a favorite, I couldn’t really settle on anything in particular.
That being said, I appreciate certain qualities in a yarn. Unlike some knitters, I am not a purist. I will knit acrylics and other non-organic fibers. The reason for this is mainly that you can pretty much be assured that no animal cruelty is associated with the creation of the non-organic yarns. I admire companies like O-Wool for their dedication to cruelty-free products (the owner states on her website, “Purchasing wool from animals that are treated respectfully is very important to me.”), but even they purchase their wool from farms that derive the majority of their income from the slaughter of their animals and sale of the meat. As a non-meat eater, this is a very difficult subject for me, as I don’t believe the meat industry could ever be referred to as “cruelty-free,” no matter how well the animals are treated while alive.
But luckily there are more and more options for animal-free fibers that are still organic. Aside from the standard cotton and linen, many sellers now also offer blends of cotton with other organic fibers like bamboo or hemp, or even banana fiber and soysilk. I’m all about feel, ease of care, and durability of the yarns I work with. If those qualities also come with a guarantee that no animals involved in the yarn production (or post-shearing) process are harmed, then all the better.