Bryan > Punk in everything, Bryan is more over and bigger draw, I would see Bryan Main Eventing Mania before Punk, I actually predict the Mania Main Event to be Bryan vs Cena for the Unified Title.
I think Bryan in general has drawn bigger numbers for his segments than Punk has ('in general' being the key words, because a lot of Punk's low drawing numbers were when he was treated as a midcard WWE Champion and turned into a vanilla babyface) but Punk has always been a bigger merchandise seller. Punk even knocked Cena off the top of the list for a brief period in 2011 (which hadn't been done except for maybe once since Cena's run began in 2005.) Bryan never has and even now, Punk is the #2 merch seller while Bryan is like #4.
This to me presents the problem when arguing who the bigger draw is - there's different ways to measure and quantify it. Sometimes guys do great in the ratings but they don't draw in PPV buys or very high in merch. Or vice versa. Sometimes someone gets a bigger pop with the crowds, but they don't have more impressive numbers than another person. IMO, Bryan and Punk are pretty much on the same level.
smh
Bryan/Cena at SummerSlam didn't draw and that's the reason Bryan has dropped back into the mid-cad. As long as Vince is having a say, Bryan will never main-event a WM. Also, I'd say Punk has been getting bigger pops than Bryan recently as the yes chants have died down. Once Bryan has a 434 day title reign I'll admit that he is above Punk.
IMO, it's wrong to assume that Bryan has been de-pushed just because of the low buyrate for Summerslam. I'm not saying he wasn't at least partially blamed for the buyrates but Bryan's push right now is going just like I thought it would since he was first screwed out of the championship. They didn't turn Randy Orton heel after all this time and push him to the top of the card as the WWE Champion and have him endorsed by Triple H as the "new face of the company" just to have him drop the title so soon after. There was clearly at least some form of long-term planning here. Most people's assumptions was that Bryan would be screwed out of winning the title back from Orton and then screwed with again in some way (I know HHH didn't say he was behind the Wyatt attacks, but he's touched upon it and it's probable that he'll be revealed as "the devil" eventually...) until it was time for him to win the Rumble. This booking would be similar to Austin being screwed out of the title in the fall of '98 and only reclaiming it at Wrestlemania the next year. So far, nothing convinces me that Bryan has been demoted in any way. What he ends up doing at Wrestlemania, however, will tell us just how much faith the WWE has in Bryan.