I'd take Backstrom right now. What Pettersson is doing is amazing, but in a tough 7 game series, the opposing team would be absolutely zeroed in on eliminating Pettersson as a factor. Even if that means "Matheson-ing" him. For the time being, i have more faith in Backstrom's ability to overcome that sort of intense physical and defensive focus on him. Especially considering, he just won the Stanley Cup.
But i'm not sure it's going to be long before this one flips for me, toward taking Pettersson.