I have not ridden either but i scoped them out before buying my Fuji Sportif.
The Giant tends to offer better value---quality per dollar, IMO. It also has the abominable "d-fuse" seat post, which means you have to buy Giant replacements. Otherwise .... flip a coin.
I had questions with tire clearance, none of which have been answered to my satisfaction.
Check this link:
https://forums.roadbikereview.com/sp...ix-364327.html where the writer suggests the Roubaix might not fit 32s .... and ask Giant owners (and Giant itself) specifically about tire clearance.
If it had been me, i would have chosen the Giant ... but Fuji offers (IMO) even better value (particularly back when Performance Bike offered them on triple points weekends, but that is over.) Check out the Gran Fondo. (I won't post a link since i am not advertising ... if you are curious, google is but keystrokes away.)