After an accident several years ago where I hit the ground square in the face, and was knocked unconscious for four hours, I will not wear anything but a full-face helmet on the road. That is what saved my life and my looks, and that is what I will continue to wear. I cannot choose for you, but that is the safest choice.
A helmet needs to fit properly. The only way to find that out is to try them on. Most people wear a helmet that is too big, and thus less safe, just for comfort because they compromised on the fit. Different brands have different shapes, so what is good for me may not be good for you. Some manufacturers, like Arai, make several shapes. Features like different sized, exchangeable cheek pads, seen with the more expensive helmets, can make the fit better, too. The right helmet will contact the head firmly, at the same pressure, all the way around. If you feel a pressure point or a hot spot just trying it on, it will be excrutiating by the end of a ride. The helmet should fit snugly, and should not be able to be readily lifted, twisted, or wobbled back and forth when properly strapped. You will look and feel like an idiot, but I highly recommend trying on the helmet you are considering, and wearing it around the store for 5-10 minutes. A few seconds does not tell you much.
If you can get to someplace like the
Cycle World International Motorcycle Show, a trained dealer can fit you. There are also a few trained Arai dealers around the country. For most other brands, the fit is up to you. I highly recommend you visit the page on helmet fit on the
Arai site, no matter which brand you choose.
BTW, my crash was in a G-Max, and it did its job, yet I wonder if I would have been knocked out in a helmet that fit slightly better. Currently I have a Fulmer and a Scorpion EXO-700. All are nice. There are several good brands of helmets that just won't fit my head, much to my dismay. My next helmet will likely be an Arai. They put me down a whole size or two, once they found the right shape for my head. My wife ended up with an Arai after searching several years for a helmet that fit right. A good helmet may be expensive, but remember the old saying, "How much is your head worth?" On the other hand, due to the helmet testing and certification requirements, if you can find a cheaper helmet that fits well, you should be assured that it will be safe. There are a lot of good helmets out there. Go try some on.