What are the best ray-tracers for architectural rendering?

It's difficult to compare different engines because it's all about scene and settings optimization. It's not safe to compare different engines if, for instance, I make a very slow rendering settings for a scene in one engine because I don't master the engine and a very fast render with the same scene in another different engine. It's difficult to compare if you know what I mean. Although the old sponza competition was very popular in the past to "test" different engines - http://hdri.cgtechniques.com/~sponza/

To me V-Ray is one of the fastest engines because once you know how to setup you can feel that things happen really fast compared with another engines but that's always kind of a subjective opinion. I've used so many rendering engines in the past (Lightscape, RadioRay, Arnold, Brazil, ...) and the speed feeling is huge compared to these ones.

Would be interesting to know if there are any benchmarks available comparing VRay to other engines. Do you know if there are any available?