I'd say offense in general. He's a far more dominant scorer than Magic ever was - both in terms of skill and aggression, and his ability to draw doubles 25 feet away from the basket/play within the flow of an offense on top of having exceptional court vision makes his impact on teammates just as good (if not greater) than Magic's. You'll look at the apg gap and think Magic was just that much better at making those around him better, but the threat of Curry's shooting stretches a defense so far out that he's responsible for creating 4on3 possesions for his teammates. He will not get an assist for this but the impact is the same. When Curry doesn't have the ball in his hands he's still drawing double teams and warping a defense because you can't allow the best shooter ever to get an open look, and that helps the rest of his team when they run offense away from him. On top of this he has strong court vision and is a great playmaker especially in the open court.
So when you combine Curry's huge advantages as a scorer and how he can dramatically influence his teammates both with and without the ball (A VERY unique trait - most players of this caliber are ball dominant, but Curry is not) it makes him the better offensive player by what Id consider to be a good margin. Yes Magic was a great rebounder, but that's not going to be a deciding point for me in the comparison and he also had his flaws defensively so no one should be using that either