I think Mike Green might be a good pick-up, but Detroit would have to retain half his contract, also Detroit would have to take Merrill and Eakin, although I could see Detroit flipping Eakin to a Wild Card team.
To date, Green only agreed to waive NTC for WSH & TBL 2 yrs ago iirc, but then hurt his neck. Last TDL he had the liver virus. I know he prefers the East coast & just had another baby. He's been rounding into form in recent weeks/1 month. Still not a lot of pts b/c we're historically bad (cap-era, if not expansion era). We could retain 50% & take on cap dump(s) depending on the return. What did you have in mind? VGK definitely need PMD's, I've been saying that since their 1st season, despite their success. Their top 7 or 8 F are sweet.
I'll add that I think Green + max 50% + 2 cap dumps would be the best in terms of cost-benefit to VGK vs the others listed in OP.
Martinez & Vatanen=costlier to acquire.
Subban looks done (way more than Green). His head & heart don't seem to be in it & his body isn't helping. Nobody is touching his contract (term & $) without a huge return...big gamble too.
Hamonic, a decent stay at home D, not the PMD VGK needs & not what he once was on NYI. I don't see CGY helping VGK as they're tyring to lock down wild card spot.