I use 3dsmax and Vray as a GI renderer. Sometimes I dabble with other programs.
LunarStudio 3d Architectural Renderings is my website/company and currently contains all of my work except for a couples images.
As a general rule, the following software accomplishes the following:
1) Google Sketchup. Basic and free. Many architecture firms use this to quickly render a simple yet artistic scene. A friend is porting over Vray (the #1 used renderer) standalone for advanced GI rendering.
2) SoftImage XSI. Modeling tool and good for animation setup. Most people end-up porting their rigging/animations over to other packages after set-up.
3) Autodesk Maya. Movie quality animations and modeling tool. Most inclusive package (and perhaps the most expensive.) Widely used in the film industry.
4) 3D Studio Max. Most widely used professional 3D software. Used in games, animations, and movies. Has the most plugins which allows it to be highly adaptable.
5) Lightwave 3D. Mac-based 3d tool. Ported over to PCs but no has a very small user base. Probably has the best built-in rendering software.