As much I'd love it, I don't think there's any way New York moves Dobson for Marner, let alone adding a 1st.
I think they'll move a solid roster player, maybe two, and the rest will be futures.
I'm terrible with value as I tend to over-consider the other team to avoid my natural biases, but perhaps something like:
Marner for:
Pulock, RD 29 (signed for 6.1 X 6 years)
-Gives us a RD in his prime, signed to a reasonable contract, and the powerplay shooter that Tre wants.
Holmstrom, RW 22 (RFA)
-Gives us a young two-way winger on a side we don't have depth. Former 1st rounder. Scored 15 goals last year in NHL.
20th pick
54th pick
or, since we're also looking for veteran 3C you could swap out Holmstrom for Cizikas who would bring grit, excellent defense with some offense, and is signed for 3 more years at only 2.5 million.