If you went by the so called "business" arguement, you could say that Rock is better than Stone Cold Steve Austin. In my opinion, he's not but that's another argument. I don't agree with those who say Rock can't wrestle because he obviously can and had some ALL TIME great matches. Rock's sharpshooter, or as I have been calling it after seeing the name at bleacherreports.com, The Scorpion King Deathlock, does look crappy and weak, but his overall moveset is both believable and entertaining.
Just go back and watch all three of the Austin and Rock matches. All great matches. Ok, now on to comparing Rock and CM Punk. My original point about Rock and Austin was me trying to say that Punk is like this era's Austin. He's not real flashy and charismatic, but he's entertaining and it's believable that he can kick your ass if you cross him. He also tells it like it is. Rock may be better than Punk, but Rock also came about in a far greater era. If WCW and WWE were still at war, and WWE put on the same crap it does now. WCW would be at WWE's funeral fairly quickly.
One thing you can say about Punk as well is that he is a self made guy, just like the Rock. Punk had the chance to be this era's Austin in popularity, but WWE buried his momentum. Now Punk is still massively over, but now it just in the "wrestling bubble". Punk had a chance to be mainstream. He was all over ESPN and other media markets. Then Summerslam came along and poisoned it. Then HHH killed it. His push has recently been brought back to life thank God, but I'm afraid he will never be as over as he could have been.
Hell, Punk isn't even main eventing Raw as WWE Champion. We all know why but I won't get into specifics. Punk can't be as good as the Rock. But hell, nobody can.