In my opinion Vray is definetively better than AR both for quality and render times. It can be scary at the beginning for its different interface & parameters hell but it's easier than what it seems. Plus if you learn it most of the features are similar in different software, I started using it in Rhino so it took very little practice to use it even for cinema4D version.
Maybe these could be useful:
http://3docean.net/item/cinema4d-vray-exterior-setup-hdrisun-pdf-guide/2713888?ref=illbru
http://3docean.net/item/cinema4d-vray-studio-setup15-materialspdf-guide/2782350?ref=illbru