Two other well respected 3D programs to consider.
MODO and Cinema 4D. Both cost money, between $1000 and $3000, depending on the version.
I use Strata Design 3D, this is a very easy to understand program, it is about half of some of the other commercial programs (~$500), but it has limitations the will bother you after a while. The animation is limited, and the plugins are very limited.
But it makes life pretty easy for my day to day illustration needs.
Physics based materials that interact with random organic particle effects are the thing that I miss most in Strata. Look for those in a package that seems easy enough to learn and manipulate.
What is the most common, or best, software for creating 3D illustrations? In the recent past there has been a discussion on ZBrush vs. Blender for 3D...how do they stack up with the other 3D software that's out there?