breather or oil cap?

Perhaps this is well-covered already, but I'm wondering if one runs a PCV valve on the valve cover, and there are two holes, what does one put in the other hole, a breather or an oil fill cap? Some say don't run a breather with a PCV on the same valve cover, others say do it. What's the story? I don't mind running a breather or an oil fill cap, but is one more appropriate than the other? It'll be a 360 magnum, throttle-body injection four barrel, if that matters.

Thanks,

Brian