Which heel in the WWE has the highest ceiling?

Cesaro by leaps and bounds.

Ziggler is almost there already. Ambrose is too early to tell (although with a bit of luck and hard work, he'll be the next cm punk no doubt). So I'm going to go with cesaro and Sandow.

Cesaro was a big favourite of mine from the indies but when he came to WWE I was fearful or his success in that he seemed completely out of his comfort zone. His matches were good from the start but his promos have really seen a sharp rise in quality. I'm super impressed with how quickly he's adapted, and how strong a heel he's been booked. He's already in that spot where all he really needs is a big name feud to solidify himself as a top name in the company.

Sandow is one that came out of nowhere for me. It's an old school gimmick that I was extremely skeptical about after seeing his vignettes from smackdown. Yet now I can honestly say he is the most entertaining guy on the roster. I don't think you could have given that character to anyone else without it simply being a trainwreck but Sandow handles it so damn well. I think he's fun to watch in the ring, but more so comedic than a genuinely talented 'wrestler'. That may not be so important in this day and age, but I do think he needs to improve his move set a touch if we're going to see him ever headline PPV's.

Barrett I enjoy, but I can't ever say I'm excited when he's on screen. He has a cool 'back story' that if WWE were smart, they'd totally play on. I like him but he's not anywhere near the level of top heel for me. He suits his position right now just fine.