Do you guys use? and why

3/16, fits perfectly to center my sight ring in my peep with just a tad of gap.

1/4" ... Biggest I can find the Fletcher Tru Peep in. It allows the most light in at those critical moments, and I just center my sight ring inside the circle of the Tru Peep....

3/16, my sight ring and peep hole line up perfectly. When I'm at full draw there is no guessing to find center. It probably wouldn't matter if I went bigger though, it would just take some getting use to.

3/16" or bigger for hunting. Like Greg said, it allows the most light in at critical moments. Anything smaller and you will be kicking yourself the first buck that comes in at last light and you cant see your pins or find him inthe peep!

1/4" for more light - I just make sure that my site ring is in the middle - I do not feel like I have any loss of accuracy

I use the 1/4 myself but I have to use smaller on my back up bow because the sight ring doesnt fit well in a 1/4 peep on the HHA sight. I have a toxonics on my 1st bow and the 1/4 matches perfectly.