Choosing a 3D Modeling Software for 3D Printing

At our MakerSpace, 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

Here are some general consideration:
- The price is important. I don't want to spend energy learning something that I will not be able to afford later.
- Since it is for 3D printing, I don't care much about texturing and not at all about animating, rigging, rendering, ...
- When I need to make something somewhat mechanical, something that fits, it is important that I can easily adjust my dimension later according to trial and errors. That's one of the main specificity the "precision" part of the graph.

Please share your choices and advices in the comments.

Disclaimer:
It is certainly not exhaustive or objective but it is based on quite a lot of reading, interviews and experiences.
This is a troll-friendly subject so please stay constructive in your suggestions to improve this decision tree.