It you wanted the biggest pop it had to be Austin, but it'd be out of character to help Cody (or anyone for that matter) and their history was already concluded, it was probably for the better to leave memories alone
The logical choice was Paul, not as HHH, just as Paul Levesque. Not only they had history together but an ongoing rivalry as authority figures. Doing a single pedigree wasn't going to kill him, but then be weird if nothing else came out of it afterwards because he can't have a match.
The advantage of it being Marktaker is that he can teleport and make people disappear so they can have quick transitions to avoid stealing the spotlight from Cody/Roman and that his entire gimmick has been showing once per year at Mania, so they can write it off as a one time thing without a follow up angle. The drawback is that he doesn't have as much history with the Rock as Austin/HHH, they were in many matches together but they were never true rivals, not to mention he if doesn't make sense for Mark to have a beef with Dwayne when he puts him over in his podcast.
