Depends on what you're hunting.. I hunt mostly rabbits, squirrels and woodchucks and the .22 is my main hunting caliber, although the .177 is also very capable of taking small game. My .177 guns do get time in the woods and they've taken many a rabbit or squirrel out to 40 yards. However like I said, I do most of my small game hunting with a .22
As for accuracy,,, yes,, the .22 can be just as accurate as a .177 it's trajectory just has more of an arc due to the lower FPS / heavier weight pellets. How accurate it is of course depends on the rifle and the shooter.
As for effective range,,,,, I generally hunt with a 40 yard or less range limit, a personal choice on my part, and my .177 and .22 rifles have no problems taking out small game out to that range....
Jeff