Helm's contract is less an albatross in both hit and term, he's ideally a 3/4 centerman, might still carry a bit of that "best third line center in the league" luster from bygone days, could be easier for Vegas to flip him in the nearish future at a trade deadline for a pick/prospect, being teams with aspirations to cup runs usually are looking for the kind of center depth role Helm could fill. Any number-crunching moneyballers on their staff might like his penchant for drawing penalties and winning more draws than he loses (lot of good that did us this year though). Injury history will give pause.
Abdelkader's label says pro-sumer power forward with grit and fists and leadershipy stuff, which might entice a new franchise looking for a piece of kit that all the good teams seem to have, despite the "from now until the end of time" contract but again the contract, and like most pro-sumer stuff you'll just end up wishing you'd saved for the professional grade version while selling your overpriced, underpowered merch at a steep loss on eBay a year or two later (or in our case, putting him out on the curb with a "free" sign). Even if their aim is just to make sure they hit the cap floor, the difference between their respective AAVs probably isn't enough for Vegas to tether themselves to that endless contract, which they'd largely get the uglier side of, without much hope of moving him (without paying a premium to do so anyway). Unlike some #8s in the league right now, ours needs much better players than Vegas is likely to have to make him anything near remotely effective in a top-six role (whereas Helm has a more definable individual effect on the ice I think, at least in his ideal role).
My guess then is Helm is the more likely of the two to be picked up if exposed, so if you'd want to lose one of them I suppose he's the one to leave unprotected. Personally I'd be happier to lose Abdelkader (or his contract at least), but I just can't see LV taking on such burden. They'll have better short-term options to reach the floor if needs be, without binding themselves for five years to a player destined to age poorly.
On a tangent while looking at their numbers, I noticed Abdelkader, up through the last lockout season, took (and won) a significant number of faceoffs, but the last five seasons he's barely taken any (presumably only taking them after someone got chased from the dot, and without much success). What happened? Was he just one of those hand-pass cheaters with a diploma from Draper's Faceoff Cheating Academy, made ineffective by the new hand-pass rule? Seems to fit the facts but I don't remember well enough if that was the case...