Vegan yarn suggestions for a hat

After I read a thread about vegan yarn suggestions that turned into something a little tricky, I would like to open this topic up again. I am looking for a vegan (preferably plant-based, maybe with a bit of synthetic) yarn alternative to the usual wool fingering I’ve been using for hats. I wonder if anybody has good experience with anything that offers the required stretchiness for the hat not to lose its shape and keep slipping and sliding on the head. My daughter, the vegan recipient, would like a simple, “classy” hat that she can also wear when on work assignments as a SL interpreter, so simple shape and pattern, but stretch and possibly even wind-resistance. I have very little experience with vegan yarns other than dishcloth cotton - so would be very grateful for suggestions and shared experience.
Thanks!

There are a variety of yarns you could use in addition to cotton. Hikoo’s Popcycle (a blend of bamboo & recycled plastic bottles) is one of my favorites. We Are Knitters also has a nice bamboo yarn. There are also linen, tencel (usually lace/very fine fingering weight), and viscose, which are all natural fibers. A variety of synthetic yarns are now being made from recycled plastic bottles which may make them more appealing than the standard acrylic yarns, though those are an option as well.

One thing I would definitely recommend is swatching and being sure you choose the right pattern for the yarn you are using. Garter stitch, ribbed, and brioche patterns can add stretch and bounce to un-stretchy yarns (my current WIP is a brioche hat out of chenille yarn). Fair isle patterns using floats and cables/ribbing can provide structure and support for very soft yarns (viscose) that might otherwise have trouble maintaining there shape. Hope this helps. Good Luck!