Ditto....nothing too hot. My 16 doesn't pattern fast stuff with a darn. It also hates Fiocchi Golden Pheasant.
Here's what really works well for me:
Fiocchi High Velocity HV16, #5, 1.125 oz., 1300 fps.
Federal Premium Wing Shok mags, #4, 1.25 oz., 1260 fps.
Kent Bismuth #5, 1 oz., 1300 fps.
All very deadly.
We mustn't kid ourselves, though. 16's don't magically kill any rooster that presents itself. There's science to it, especially if we're talking about the Game Loads mentioned by JMc above. I think I'm right that those are s...l...o...w loads. At something less than 1200 fps, especially w/ small shot (6's or smaller), they simply won't have the energy to penetrate a rooster or break critical bones much past 30 yds. Might get a golden BB in the head or boiler room, but that's pushing it. Thus, my preference for #5's & velocity around 1300. Factor in a modified choke, & you get an honest extra 10 yards of effective range. That's the science. The art is putting it in the right place at the right time. IMHO