There are two kinds of modelling workflow you need to consider. Forget about what is the best “big brand” or free vs payed.. thats not something that should affect your decision on what kind of modelling you want to do.
Of the two methods I’m going to explain..
1 one may work well with your existing skills.. and
2 or you may prefer the other which will give you the complexity which is what I think you might be really looking for.
You might windup using both at some point, so its best to try both of them(or at least read up on both).
Solid Modelling and Surface Modelling(detailed description – Solid modeling ..surface modelling has a simillar workflow)
In programs like Rhino, Inventor, AutoCAD (and solidworks and others) once can model objects by inputting precise measurements and geometric parameters.
Eg: if you want to build an organic arch out of steel rods like this
Portal of Awareness, An Arch Made Out of Coffee Cups in Mexico City
You would input the length of the rods, and a few simple parameters for the bends.. all these parameters can be easily translated to the real world.. when you have to get down to actually constructing it.. or give an instruction manual to someone else.
However with this method you will be limited by the rules of geometry.. and only very experienced modelers are able to use this method to create something as complex as a fluid form one would sculpt out of clay.
Mesh Modelling commonly called 3D modelling in Computer graphics
This method is typically used in programs like Maya, 3DsMax, Blender
(Zbrush and Sculptris use a different workflow but are more compatible with mesh modelling programs than solid modelling ones).
A mesh model consists of vertices, edges, and faces that use polygonal representation (including triangles and quads) to define a 3D shape.
You can then modify mesh models in ways that are not available for 3D solids or surfaces. For example you can apply creases, splits, and increasing levels of smoothness. You can drag mesh subobjects (faces, edges, and vertices) to deform the object. Clay like sculpting is achievable and is usually done with Zbrush or Sculptris(free) .. Blender also has a sculpt mode thats fairly good.
Example from one of my old projects:
A wildlife photographer and a product designer sent me this picture of an otter..
They needed me to create a model of it that could be 3d printed and used to create a cast for some teracotta clay statues people can put in their garden ponds/fountains..
Because I used Blender.. I was able to make multiple iterations to the design and get it all done in days.
heres the viewable 3d model –
So in a nutshell, think of the kinds of projects you want to be doing.. and then decide on which 3d workflow is best for you.
Unlike solid models, mesh models have no mass properties(necessary for running simulations etc..). For 3d printing the model has to be exported to stl or other solid formats(a simple process).
Sketchup is a fun maverick.. I’m not sure where i’d put it. Mostly under solid modelling .. though its much easier to use.