Seth was never given the chance. The booking for his title reign was terrible.They tried Seth. He main evented WM and got several victories over Brock but he flopped miserably and is pretty much a mid carder now without any face or heel identity with no potential to ever be taken seriously again. I'm not saying that as some Seth hater. It's just what happened. Not everyone can be a Cena and Reigns and overcome the crowd turning on you.
Daniel Bryan is the only real answer but unfortunately the injury problems he had takes that away. By the time he came back his ability to be fotc was over with.