Just got back from Egypt.
I think it's a toss up b/w both FS properties. Can't go wrong with either.
I prefer the spa and location of Nile Plaza. The in-house Chinese place is amazing.
That said, I think overall I prefer the one in Giza. The Lebanese restaurant there is one of the best places I've ever eaten. I like the more boutique feel to the place. I like that it's more of a "salt of the earth" neighborhood. And, I like the staff/service - hands down - more at First Residence.
But again - can't go wrong with either. Honestly, I'd consider staying at both...they're both wonderful properties.
If main attractions is your only criteria, Nile Plaza is it.
Made 5 albums from my Egypt trip....4 of them are of hotels...check out Nile Plaza and First Residence.
https://www.flickr.com/photos/117624978@N08/sets