Ok I am in arch vis too using vray. Vray is slow and painful if you dont have renderfarm, constantly updating your processor and software. Vray give you realism but you lost too much time on that, UE is real time, and if you take that time is money, UE all the way. I think future is in real time rendering. Everyday they update and bring some new processors on market so rendering time is dropping and quality is rising, so my opinion with UT and his almost realistic look you cant miss it, it has enough quality for clients that doesnt have vision.