High-quality Nolan modular helmet with metal hinges and clasps. All Nolan modulars have a 100% "front stayed shut" rating in the UK SHARP testing. But when you come to a stop at a red light on a hot summer day while touring all day, it takes half a second to flip it open, drink some water from the water bottle on the cup holder, and then close it again and ride along.
I love having a cup holder for that reason alone, it's easy to get dehydrated on the bike otherwise. And that can lead to all kinds of issues with focus and concentration, to say nothing of cramping if it gets really bad in hot weather. A cup holder is a fantastic long-distance ride accessory. Sure, you can wear a Camelbak or have one in a tank bag but that's still a bit of a pain.