I may be biased, I do really like Zibanejad a lot. But in my mind, a sensible move - in terms of setting the club up for the future while also remaining competitive this year, would be to trade Del Zotto and a prospect, let's say one with relative upside like Fast or Kristo (and no I don't view either a throw in, i'm very high on both) for him.
Understanding that Ottawa has an internal budget, and that there's roughly 1 million dollar's in difference between Del Zotto and Zib, the Rangers could further sweeten the deal by eating that difference. Under the new CBA they'll be able to eat up to half of Del Zotto's salary.
Now, let's say that Ottawa accepts this offer. By no means does this assumption mean they'll do it in reality, but let's assume that for the point of argument they accept it.
The Rangers could then bring up McIlrath to assess his development. Let's say this deal happens before Christmas and McIlrath is given give or take a month and 3/4 (Excluding Olympics) to show what he has.
At that time, the Rangers can decide on Girardi's future. If McIlrath is viewed as first pairing material, Girardi would (and should) be moved for the success of the franchise moving past this year.
Meanwhile, we have just traded for our 2c that we are in desperate need of.
Back to reality, if Del Zotto can somehow net Zib, i'd say it would be the best move of the club. It fills a need, even if we're giving away a prospect, and helps the club assess other assets and what they're worth to the team moving forward.
Girardi shouldn't be in the longterm plans. Furthermore, Moore needs to be played over Falk, eventually. Staal is the next player up in terms of assessment relative to worth to the club. Rangers management needs to see what they have in Moore and in McIlrath before either Staal or Girardi are moved.