I would take Malkin over Crosby.
I think skillwise, Malkin is as good a playmaker as Crosby is, he can also pull off the dekes like Crosby can, and he's shown that he has a pretty good wrist shot. I think in this department, the two are pretty close in and objectively, I don't think anyone can say who's better.
Where you can say who is better, is probably one on one as I doubt Malkin can deke out Theodore or Esche on a breakaway the same way that Crosby's done it, but the area where Malkin has a big advantage in is his size. Malkin is 6'3 and is a big physical presence. The kind of presence that Crosby will never be able to deliver because he's simply smaller.
I think this is the big difference between the two, and I think it will prove to be as an advantage to Malkin. That's why I would take Malkin over Crosby..