a car of choice needs to make sense for the owner (or lessee). even if you drove 2 cars back to back and reviewed it, it's still just an opinion based on one's background.
but the truth of the matter is, these are 2 very different cars targeted at 2 different demographics. i just happen to fit in the 370Z demographics more so than a genesis coupe.
i'd get a new G37C over a genesis coupe if something happened to my G35C as it's non replacable. if something happened to my Z i'd get another Z. i wont be looking anywhere at a hyundai catalog that's for sure.