For the past 14-15 years I've used some type of tritium pin, with the largest peep site made by Tru-peep, or a similar sized hole. There are also a couple of peeps on the market that have various sized holes in inserts that can be screwed in and out of their peeps to change the size hole. Those type of peeps are nice in that if you want to use your bow for some target league and experience optimum accuracy, you can just use a smaller-holed insert. But, for hunting, I actually take the entire insert right out so that the hole is the largest it can be.
With a large-holed peep, and a decent tritium pin, you can basically shoot any deer, as long as you can see it well enough to shoot with your eyes.
A lot of guys don't like the large tritium pin, but I've found they seem to last they longest, and once light fades, you only see the glass portion of the pin that houses the tritium, making it a much smaller sight pin. When that pin is just used as a 20 yarder, it is still more than adequate to allow for consistant accuracy. At 40 yards it wouldn't be too great, but at 20 it's just fine. No batteries, no long wires to break, no switches to turn on or off, just a nice, dull, glow that can be seen from 20-30' away in the dark.
For my 30,40,or50 yard pins I like a very small fiber optic. Right now I'm using a Tru-glo sight, with a Tru-glo tritium pin. The brightness is OK, but I may try and figure out a way to stick a large tritium head back on just to make sure I can see in any situation no matter what.