Mirajane >>>> Jellal = Laxus = Mystogan. Those three r on the same level but i would put Jellal alittle bit above the other two. But logic power Mirajane can defeat all of them at the same time, y? Here is y.
As #She-#Devil Mirajane can shatter mountains with her bare hands, plus her attacks r soo OP and she is fast, durable, reflexer etc, i would put this mode of Mira on the same level as the others.
As #Demon #God #Halphas Mirajane can distroy an entire city with a single blast, she even made She-Devil look like a piece of cake. And she was powerful eneough to overcome Racer's ability with ease, she is beyond the others.
As #Sitri she was confirmed to be the strongest Take Over in the GMG by Erza, tho she lacks feats as Sitri we know that it is above She-Devil. Mirajane has almost no feat that even adresses her as an S-class mage bcz she is too powerful to be used.
As #Alegria she was sooooo powerful that even her mere presence made the nature go nuts, no one has shown that kinda level of power so far. Making the nature go crazy by ur mere presence is a kinda a cosmic level threat. And it is the most powerful Take Over so far, plus i would adress her to be on the top 5 most powerful mages
As Seilah she might not be that powerful compared to Alegria, Sitri or DGH but What makes Seilah so dangerous is her curse mark MARCO, she can instantly take control over anyone and can make them do anything she wishes. That includes even Acnologia i suppose.