peep, ghost ring, or traditional irons?
Or any other non optical type, what's best?
Do any perform ok in low light?
The correct name for a "peep" sight is "aperture" sight. They have long been considered to be superior to all other iron sights (non-glass lens), since at least WWII.
As to their effectiveness in dim light, I had a Williams aperture sight mounted on a rifle one hunting season, years ago. The sight had a large aperture and had a brass insert surrounding the aperture opening...it was supposed to be and intended for superior for dim-light shooting. Long story short, while in the river flats at about five in the afternoon, with light already failing, I sighted a deer (buck), about sixty yards away from me.
This is where that sight was supposed to come into its own. However, I had a very hard time getting a sight picture, and the deer had stepped forward, putting a tree between himself and me. I had a blow-down just in front of me and I figured if I stepped over it, I could get a shot at the buck, but figgured that when I did, he would hear me, stop and look in my direction giving me a standing shot. It worked like a charm...I stepped (hopped), over he stopped and looked in my direction, giving me nearly a broad-side shot. I fired and he dropped. But...I never used iron sights of any type from then on for deer hunting inasmuch as the most productive deer hunting is in the two twilight times of the day here in Michigan.
Scopes for the superior sighting in poor light. As much as I loved the aperture sights since my Basic Training with an M1 Garand, I reluctantly have to admit that they are not much good in the low-light because they cut down on the amount of light entering your eye, when you could use a whole lot more.