I'll break from the crowd here and say Winchester Super-X Powerpoints. They're a full 40 grains and have a wicked hollow point. I haven't shot them out of a handgun, but from a rifle they're real effective on anything I've shot, up to critters a 22LR has no business taking down.
Nothing against CCI, though. MiniMags, Stingers, and Velocitors are all rounds I've used a lot and they all work real well, too.