Peep sight choice is very personal. Only you can choose the one best for your style of shooting. The craze lately has been to match your peep diameter to the sight housing. I personally hate doing it that way and always center the pin. But I rarely stand hunt and too often take quick shot opportunities. Guys who say that is not as accurate need to tell that to Randy Ulmer

I spent a few years trying the sight guard method. Infact I started making the 7/32" peep aperture just for my own bow, draw and Spothogg sight. My accuracy at the range was great, but my accuracy in the field was poor. I was still tagging animals, but I was missing my spot too often. And I really like watching my animals go down in sight and avoid having to blood trail.
The subconscious mind naturally centers things within a circle. If you consciously center a circle within a circle and then try to concentrate on a single pin amongst multiple pins not centered within that circle and then try to focus all the concentration you have left on the target it goes against the minds natural order of things. Your primary focus should be on the spot. Your secondary focus should be on the pin floating within that primary focus spot. If you do this you only need a slight shading of the peep housing for your mind to get all things centered perfectly. Shoot fast, shoot slow, shoot with perfect form or shoot at an animal behind you under a branch from a crouch it should all center if your concentrating is completely focused on the spot.
Shoot a single pin centered in the middle of your sight housing and you have the best of both worlds. My main hunting partner "Crazy Larry" does it that way and is one of the best
in the field shooters I have ever seen. If not
THE best in the field shooter I have ever seen.
RAD, Inc. has over 140 different peep sight and peep sight accessories in the catalog. If there was just one perfect way to use a peep we could eliminate about 139 of those sku's.