There are almost as many contentions when discussing helmets as there are motor oil. All helmets sold that are DOT approved will protect your head during a crash, and if you live in a helmet-optional state, wearing any helmet is better than not wearing one. Snell-approved helmets are tested to higher forces, but in practical applications it probably doesn't matter much. The difference between Snell vs. non-Snell helmets is tiny compared to helmet vs. no helmet.
The best thing you can do is pick a helmet that fits you well and will not be a distraction while riding. Do not under any circumstances buy a helmet that you have not tried on. Go to a big m/c store and try on lots of helmets from lots of brands and pick one that fits right. You don't want to be adjusting your helmet while riding because it doesn't really fit you right.
The additional cost of the more expensive brands is usually in materials and features. I liked my old HJC helmet just fine, but the extra cost of my newer Arai helmet was well worth it. The lining is much more comfortable and it fogs less than the HJC.
"We didn't trade shoves; I did all the shoving." -Bobby Knight, 1981