Most are going to disagree with this but i think the person they need is someone who already is being pushed to the moon, Deangelo Dinero (The Pope), simple fact the guy gets an amazing pop when he enters the ring.
His ring work is on par with Cena, he can tell a story and work a good match with anybody, weather it is AJ styles high flying style, or the technical expertese of Kurt Angle, the guy can work with almost anybody, but heres the catch he shouldnt get his opportunity at the next PPV (Lockdown i believe) He needs to be teased and distanced from the title but has to be shown chasing it, If they really want to make AJ a heel they need him to foil any attempt that Dinero has at coming close to the belt, he needs to keep chasing AJ until he eventually gets his match at Bound for Glory, if they do this i guarantee it will give dinero enough time to get the crowd behind him and with that momentum they can position him as the TNA babyface champion.
This has worked with numerous faces, look at the whole Sting/Hogan situation, if they actually made the blowoff work it would have been amazing, and would have given sting the momentum to take the company to the next level.
Look at Joe vs Angle (if done properly) they would have been able to make Joe TNA's top face.
Or if you want to add to the momentum Austin Vs Mcmahon, (positioned Austin as the companies top face single handedly carrying the company.
TNA needs to strike while the iron is hot, The pope has enough momentum and the best chance of carrying the company to the next level if they keep him away from the title for at least six months having AJ cheat his way out of the title match.