Well, statistically Dats always made everyones Corsi significantly higher so the advance stats answer is probably Datsyuk. But actual goals/assists (the end result so to speak) wise, Z made Hudler, Filpula, Samulssen, Larkin, Mantha, Abdelkader, Nyquist, Tatar, Brunner (the list goes on.. Bertuzzi, Cleary) all look like top 6 players, or better top 6 players. Most of Datsyuk's linemates were the better wingers on the team like Hossa, Franzen, Holmstrom, even Zetterberg himself. Towards the tail end of his career Datsyuk got stuck with Richards for a while though while Z got to play with Nyquist.
Having said all that, if Zetterberg was ever slumping, Datsyuk was always the go-to player they put him with to get him going. The same wasn't true for Datsyuk, he rarely lost consistency and if he did, he usually found it back himself