I was digging into the prospects a bit more, and I think Carolina has far and away the best prospects to offer for Guentzel. It's not even close, all of Nadeau, Koivunen, Nikishin and Morrow are sitting on top line upside or better according to Dobber Prospects. If you could pull off Nadeau and a 1st, I think that would beat any offer another team would make.
If not Carolina, I actually think Florida is the next best option. I love what I see from Samoskevich and they have a couple of decent secondary pieces between Sawchyn (who I think the Penguins should target if they're trading Smith to Florida) and Devine. I actually don't know if the Penguins could pull off Devine in addition to Samoskevich.
Vegas has multiple good prospects, but not really any obvious headliners. I think Brisson and Hoglander actually seem pretty similar in upside, which is below any of the Carolina prospects or Samoskevich. Vegas has a plethora of good pieces, but no real headliners that stand out. But if you'd be fine with a bunch of B prospects and a 1st for Guentzel, Vegas would likely give you exactly that between Cataford, Sapovaliv, Brisson, Korczak and Dorofeyev. Lucas Cormier also had a really good prospect rating before this year, but he has really fallen off.
Vancouver....yikes. Hoglander and Raty only have 2nd line potential, and Podkolzin and Pettersson aren't even rated at 2nd line potential. Even Lekkerimaki isn't rated all that strong, he has 1st line upside but is ranked below Devine from Florida.