To you immediate question I prefer Huberdeau. In a limited keeper [especially one with only 7 slots] prospects are often over-valued b/c of their tempting upside [which many don't reach until their 4th season]. There will also always be a plethora of top-end prospects available in your draft who simply haven't "broken out" yet.
Given some of your top end, young, and more proven talent Grigs is more than expendable IMHO.
9 Team [keep 10 + 3 prospects]
Scoring F=1[g/a]; D=2[g], 1[a]; G=2[w], -1[L], 1[OT], 2[SO] Top 12 F, 6 D, 2 G count
Crosby, Ovechkin, Backstrom, Huberdeau, Moulson, Pominville, Lucic, Grabovski, O'Reilly, Elias, Backes, Oshie, Wilson, Dubinsky, Desharnais, Bailey, Neilsen
Byfuglien, Letang, Goligoski, Carlson, Faulk, Gonchar, Martin, Krug, Trouba, EJ