I learned something this year at the ATA that I had previously never givin much thought before. PEEP COLOR, in the past I had typically just installed a peep that matched any other accessories on the bow. What I learned is that everyones pupil procesess light differently (knew that actually but hadn't givin it any thought in relation to a peep. So they guy had 6-7 different color peeps on a lil card and had me look through each one till I noticed something. What I found was with every peep I could "see" the peep, a halo of the peep color in my sight picture. EXCEPT for GREEN. My eyes liked the green peep and no fuzzy halo was present, just a clear circle with no color or fuzzy halo present resulting in a much cleaner sight picture. Many of you may already know this but it was new to me and something I had never previously givin much thought to before.......... IMO, now this is just as important as peep size.
I run 3/16... works perfect on my setup. Like everything it sort of depends on the shooter and the setup etc. But I generally would air on the smaller side. Aim small, miss small is what they say.