Polyester ropes can be made soft but still remain durable. Typically used for main, jib, genoa, and spinnaker sheets on cruising boats where gloves are not always worn. The single braids are exceptionally nice for non-winched applications like jib sheets on smaller boats or mainsheets on cruiser or racer/cruisers. Double braids, polyester cover over polyester core, in this category are capable of being used for winched applications as found on larger cruising boats.
While offering great durability and UV protection, the trade off to polyester is that it will absorb water, so for racing applications a dyneema blended single braid is usually preferred. Moderate stretch is acceptable on cruising boats or with Dacron sails. It can even be beneficial by acting as a shock absorber.