Well some think he is on the level of Vergil and Dante now which is dumb
He did what Arkham did in DMC3 ,which was besting the sons of sparda after they fought all out for almost 25 minutes straight and were stamina depleted and weakened , I mean Arkham made Dante and Vergil look like a joke , as in peak condition they would have stomped him without any effort
So I don't think a fresh Nero besting a weakened and exhausted Vergil is that huge a feat , having said that his regular Dt may be more powerful than theirs is , but he would need his base form to be a lot more powerful to match their current regular Dt or base forms in 5 in his base or dt
If I was to guage his strength now I'd say ya he is above Dante DMC1 pre sparda Dt
But below sparda Dt Dante
Him and anime Dante would be a hell of a fight
In or around that ball park or maybe just above
Behind Dante from DMC2 or 4 or 5 though
Just in my opinion