I cut my teeth on a Williams peep sight atop a Lee Enfield .303, took my first two muley bucks with it. IMHO, peep will always prove more accurate than a traditional buckhorn style. Notably, your eye automatically centers the front sight to the peep without having to think about it. For poor light, as mentioned above, remove the aperture ring and carry on. Nothing wrong with Williams, provide for pretty fine adjustments.
I once sold a Marlin 1895 in 45.70 to a fellow, who then asked about better sights. I recommended the Williams peep (which we didn't carry). He came back a couple weeks later just to thank me, said it turned his rifle into a real shooter.