Although you can find photos of cracked, shot and crushed Aimpoints and EOTechs that refused to die, one day those iron sights are going to save your butt. There's only one trait to consider here: Reliability. The rear sight will likely be folded obediently beneath your optic until you really need it. At that point you want it to flip up without extra button-pressing or knob-twisting. You also want it to be able to hold a zero and not pop up when it's not needed. Same goes for the front, but some guys roll with a non-folding front sight so they can aim over the top of their optic for really close fights.
What they said: "If your primary sight uses batteries, eventually it will have an electrical problem. I hope that when it happens, it's not when you're fighting for your life. But if it is, BUIs and training will hopefully allow you to prevail."
Operator Favorite: Troy Folding BattleSight set ($250)
Troy was widely chosen as the backup iron sights of choice. They stay closed until needed and flip up easily with no controls. Folding requires a hefty button press so they won't fold until you want them to. Once they are open, it's going to take a 1000 lb accident to shear the cross bolt holding the sight up.
Made from aluminum and stainless steel, they should last as long as your rifle. Mount them on a Picatinny rail, use a bullet tip to adjust in .5 MOA clicks and know they are there when you need them.
