Here is an article I found on riding helmets. It’s produced by a group called Risky Head, which specializes in reviewing all kinds of helmets. The article has reviews of their top 10 picks for riding helmets along with a buying guide. Wearing a helmet designed for riding reduces the risk of dying as a result of a fall by 70%-80% !!(Source)
They also have a top 10 guide for motorcycle helmets, which can also be used with ATVs. Wearing a motorcycle, motocross, or ATV helmet with a face guard reduces the risk for head injury by 64% (Source).