Aside from only the allergy concern with wool yarns, Acrylic yarn has a tendency to hold it's shape and color longer than typically found with wool or blends. Knitters know that one hundred percent wool yarn will need special care when washing and drying, and acrylic knitting yarn does not have that restriction.
Working with man-made fibers is easy to transition into if you have been working exclusively with wool up to now. The patterns do not change, but the finished project is much easier to care for. Acrylics can be very soft, like the blends for a baby blanket, yet sturdy and strong enough to hold up for years.
Acrylic knitting yarn is what is considered vegan friendly as well, since there are no animal products used in it's manufacture. While the sheep the wool yarn come from are not killed for it, it is still taken from them. Therefore sheep wool is frowned on by vegans, who want to see all animals treated with dignity and compassion.
Acrylic yarn comes in a wide variety of colors and thicknesses to choose from. Rug yarn and ultra fine yarns for detailed crochet and knitting projects. Also everything in between can be found to make your projects really stand out.
Another benefit of acrylic yarn is it's resistance to moths while in storage. Moths are attracted to wool, but the sweaters and winter wear made from acrylic will not attract them and be ruined. It is as warm and comfortable as wool garments without the allergy or pest problems associated with wool.