Which 3D software should I learn for 3D printing?

[update] Added: FreeCad and Autodesk Fusion 360.
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At our [MakerSpace](http://www/micorfactory.be/), I am often asked for advice about what should someone use in order to create 3D objects for 3D printing.
There is not just one single answer because it depends on a few parameters so I made a little decision chart:
http://www.gliffy.com/go/publish/5271448

Please share your choices and advices in the comments.

The 3D files are there as exemples:
- The octopus is a Typical exemple