Without doubt, FS Nile Plaza is currently the best option in Cairo, whereas FS First Residence (different owner, by the way) has really fallen from grace over the past few years - not, I think, because of FS, but because of ownership issues.

Sofitel Gezirah is a very, very acceptable choice. I actually preferred it to FS First Residence this time.

Once Oberoi finish the big refurbishment of Mena House, then this too should be a serious option (as long as you stay in the old, original wing).