Sheogorath is the only Prince that I see havering a shot at him because he is completely unpredictable. How can you determine the fate of somebody that literally can take fate and turn it into a song bird.
Sheogorath is also possibly as strong or stronger than Jygalag, considering he is basically a corrupt form of him that gained its own personality. He managed to defeat him during the Greymarch as well. (It was in their shared realm so you can't use the argument that being in SI gave him an advantage) The only reason he seemed mortal after Shivering Isles is to keep the gameplay balanced. (Even then, you get a spell that essentially prevents you from dying)
So I think:
Sheogorath>Hermaeous Mora>Jygalag>Molag Bal>Merunes Dagon>Boethia>others>Peyite.

