I prefer fixed sights, but flip ups are nice if you run a glass optic with your gun. They're out of the way when you don't need them and there when you do, which is the point to them. I have a larue fixed rear/Troy fixed HK front, the HK style front makes it easy super easy to line up. I also have Troy flip ups and KAC 200-600m flip ups, and I like them as well.