>>1159187In person. Buy the one that is most comfortable. Secondly buy the one that looks good on your head. If you want to be a jew, then go and buy it online, but you have to try on a helmet, the comfort levels vary, and they're different for different people. Size matters a lot, you really do not want a helmet that is on the large side for your head, as it will be ungainly, too small is even worse.
More expensive helmets will typically be lighter, have higher quality fit systems and general build quality and better ventilation so they stay cool. They aren't safer though and they aren't necessarily more comfortable, especially between midrange and high end ones.
Pic related is what i use, and i like it a lot.