Radian raptor charging handles are a must in my opinion - Radian Weapons Raptor SD Ambidextrous Charging Handle

I literally now have one of these on every ar15 that I own, I love them that much. It's super nice to be able to charge the weapon with only one finger from either side of the rifle. Not only that, it's aesthetically pleasing to the eye, and makes for a more "custom" look. Anything that makes my rifle easier to use makes it worth the money in my opinion. A few seconds saved can possibly save a life when it comes to a defensive rifle.