Nothing against Triple H, but I think you guys overrate him if you think he's the best heel ever. He was only good because of his association with the McMahons. He was moderately irrelevant for the most part until he fueded with The Rock, who was also a better heel than HHH imo.
HHH would get my vote, but I don't know if he's the greatest heel of all-time though. Wrestling existed before the AE and RA eras, but for my generation HHH is by far the best.
2015 Favorites WWE/NXT:
The Heel Overlord and COO Triple H/Seth Rollins/Shinsuke Nakamura/ AJ Styles/ Sasha Banks/ Finn Balor/ Roman Reigns/ Kevin Owens/ Dean Ambrose/ Randy Orton/ Charlotte/Apollo Crews/Stardust