Every helmet sold in the United States has been approved and must be approved by the Consumer Product Safety Commission. So, from that standpoint, they are all safe. The difference in price is generally a reflection of how many vents it has, not it's relative safety. The more important consideration is that it fits you and that you adjust the straps and wear it correctly. So, I strongly suggest that you go to one or more local shops and actually try on a variety of helmets. Giro and Bell are two of the bigger names, but they are actually the same company. They each fit slightly differently and you'll often hear people say that they either have a Giro or Bell shaped head. I have a Bell head myself, but even among Bell helmets, some fit me better than others.