Sorry to hear that the past couple of years have been difficult.
From your description, it appears you are deciding between 4 nights on Norwegian Sky and 5 nights on Navigator of the Seas. So, ship size and cruise length also come into play.
If it were me, I'd go for Royal Caribbean mainly because it's a longer cruise. I also like having sea days at the beginning (to decompress) and the end (to pack at leisure). Both are good lines/ships, yet the Royal Caribbean itinerary is more appealing to me, personally.