Iron sights never fail, are never out of battery power, are always there.
Aimpoints are great. The newer clone magnifiers are not bad at all. With a quick detach base they can be secure and put on/taken off quick.
I must note this though...if you are going to buy clone 30mm mounts for your magnifier and aimpoint...buy two of the exact same mounts, same brand, same style.
I've got a box full of mounts and very few combinations line up perfectly. Either the height is off a bit (close but off), or the centerline alignment is out.