I went through the same decision for an Encore pro hunter here as well - there are a couple of my posts about it here on the muzz forum.
I wound up looking at a couple of different peeps - I started with a Williams WGRS, then I tried a Williams fool proof adjustable, and I finally settled back on a WGRS style peep that is nounted on a scope mount so I can switch back and forth between scope/no scope depending on what state I am hunting (EABCO is the mfg) and with the front sight I settled on I didn't see the need for the adjustable peep.
Several of the guys on this board helped me with the front sight option too - I tried a front gloge sight - specifically I bought a lyman 17 aml and a williams shorty ramp and had that installed on the gun with a crosshair insert. In the daylight this was very accurate but it severely limited me at low light, and since most of my deer hunting is in wooded areas in MN I needed the better low light capabilities more than I needed the extra yardage that the crosshair front sight afforded me. With that in mind I switched back to the factory fiber optic that came with the gun and it has been working just fine. I also bought one of the Tru Glo globe sights but I didn't care for the position of the tru globe ghost ring - too far from the eye.