It would have to be The Shield, for this main reason.
The match alone legitimizes The Shield in a huge way. They beat all these superstar teams, having Taker want to fight them just legitimizes how much of a threat they truly are.
If Taker is coming back to take you out, you have to be legit.
Also Punk/Brock don't need the rub from Taker and while we all know Taker's gonna win, the Shield putting in a big performance would do much more for them than it would for Brock/Punk
The match alone legitimizes The Shield in a huge way. They beat all these superstar teams, having Taker want to fight them just legitimizes how much of a threat they truly are.
If Taker is coming back to take you out, you have to be legit.
Also Punk/Brock don't need the rub from Taker and while we all know Taker's gonna win, the Shield putting in a big performance would do much more for them than it would for Brock/Punk