I think the thing to consider when comparing the Pipe Bomb and the Austin 3:16 promos what happened after both of them. When Stone Cold cut that KotR promo he was still walking out to the old Ringmaster entrance music, and he was moving up the midcard. He would later get his classic glass shattering theme, start having important feuds over the IC belt with the likes of Rock and Owen, and then rise to the top position in '98. He was then given the ball to run with it, but the key thing is that Austin was still improving on his character while growing in the company. The Austin 3:16 was basically a promo that said, "I am here to kick ass and take names, you sons of *****es!"
With Punk, he was already a well traveled vet by the time he got in the WWE. He had to deal with a lot of politics before he could really get a chance to show his character. Then he had a lot of moments where he would start and stop. They put him in a championship position a couple of times before the Pipe Bomb promo, and that's before he even had the Straight Edge Society. He was basically the guy that the ball was being dropped on, and the fans knew it. When the Pipe Bomb promo hit, he basically verbalized a lot of fans' anger as the poster child for misused talent. His promo was basically saying, "I'm pissed because you won't get your head out of your own ass." He didn't need to rise as opposed to being needed to not be wasted in a spot that he'd long outgrown.
When you take into account the big difference between the two points in time with both promos you see how the Austin 3:16 promo is looked at more fondly than Punk's Pipe Bomb. When it comes to the quality of both then that's a personal debate. Both have their merits. Punk at that point had a firm grasp on who he was in the wrestling world, so he had a better flow than Austin, but Stone Cold's promo had more of a clear point besides the rant of the Pipe Bomb. But in terms of significance? Austin's wins hands down because that led into the biggest time period of the company's history. Punk's Pipe Bomb could have done that, but booking let the heat from that promo down shortly after it. Punk did become a star that connected with lots of fans, but here we are years after the fact still *****ing about why he was misused instead of looking forward to what he's going to do to entertain us next. Still stuck with the same John Cena that he *****ed about. Not much has changed at all, so it's impact on the business wasn't what it could have been. But Austin's booking went from a cool promo to him going on a tear that got everyone behind it. They actually lived up to the potential with him, and it changed the business.
So basically what I'm saying is that it depends on what you prefer when it comes to "greatest mic moment" in sports entertainment. Does great meant business impact to you, or does it mean quality of the promo? If it's quality then you can debate the two until the cows come home since it's subjective. If it's business impact then Austin 3:16 is the obvious answer. That's not Punk's fault that it ended up this way, but that's how it is.
That list is null and void though without having any of The Great One's promo's though.
