99% of the time I agree 100% with Mike but you seem to be a different kind 1st timer. Having shot Ken's and selling them in the shop I can vouch for POF's quality. Take a look at Daniels Defense too.
Well, yes and no. If you have a place to do it (I have my own ranges), punching paper CAN be entertaining if you set up 5 or 6 cardboard silhouettes at 25 yards and shoot offhand against the clock to put 2 holes in the vital zones of each one in a total of 6-10 seconds. With a timer on your belt you can run this drill by yourself....
My only gripe with ARs is a lack of good things to shoot at; punching paper really isn't all that entertaining, and plates at realistic distances will be cratered.