This was the era of "faking it." You spent hours tweaking Irradiance Maps and Light Caches to avoid splotchy shadows. If you had a "hot" version of 2.4, you were likely using it in 3ds Max to create the first wave of hyper-realistic arch-viz that blew clients' minds.
While the latest version is usually the most advanced, certain versions created a "hot" buzz due to revolutionary improvements that changed the industry standard. vray+all+versions+list+hot
: This era introduced the Adaptive Variance Sampler , which drastically cut render times by focusing on noisy areas. It also saw the expansion into Maya, SketchUp, and Revit. This was the era of "faking it