The Vishanti are the top magic users in Marvel. The only ones who might be able to beat them are the Trinity of Ashes (being their counterparts), Archenemy (since he absorbs magic), and Zom.
I don't know enough about the DC magic elite to comment on them.
And The phantom stranger is the strongest magical user in dc with the exception of the spectre. you guys keep on forgetting that the spectre is omnipottent and according to dc the stanger possessed enough power to be a near equal of the spectre. the spectre only obey one person in dc and that is the presence and the phantom stranger on obey one person in dcu and that is the Word/ as he called it the Higher Authority which is also the presence. He is the one of the few characters in DCU immued from the spectre judgement the other two are Michael and Lucifer. without the presence restriction the Phantom Stranger becomes dues en mechina meaning he can end any conflict with the wave of his hands
even with the restriction the phantom stranger is still a spectre level cosmic/mystical entity who in order for the omnipotent spectre to kill will means he had to destroyed all magic in DCU. anyone darksied fear is not someone to take lightly
Agg' is by far the weakest member of the three and he stalemated Galactus. When they pool together their multi-versal powers, they create a new power that supposedly puts them close to omnipotent.