Personally, I would Like to see Orton vs Punk. I think they would mesh well in the ring and put on some great matches and the interactions between Orton (who's whole gimmick revolves around not giving a fuck and doing what he wants) and the SES would be gold.
The huge money feud would be heel Cena vs face Orton. It's only a matter of time before Orton overtakes Cena as the top face in the world. He has the crowd fully behind him and is consistently receiving pops just as big as Cena's. This is the feud that would solidify Orton's legacy and finally put him in his rightful place as one of the greatest wrestlers of all the times. Cena is in need of a gimmick change and its time for him to return to his heel roots.
The huge money feud would be heel Cena vs face Orton. It's only a matter of time before Orton overtakes Cena as the top face in the world. He has the crowd fully behind him and is consistently receiving pops just as big as Cena's. This is the feud that would solidify Orton's legacy and finally put him in his rightful place as one of the greatest wrestlers of all the times. Cena is in need of a gimmick change and its time for him to return to his heel roots.