MeshMixer is a 3D design and modeling tool for 3D printing or scanning, supported by Autodesk (acquired 2011). While not discontinued, the product will not receive updates and Autodesk states they intend to include all functionality in updates of Fusion 360.
Product Designer / Owner in Engineering at IDZone (1-10 employees employees)
Pros
Auto-repair function works fast, and if it does not completely cover all problem areas, manual fixes will work 99.5% of the time.
Remeshing algorithm is fairly slow but does a wonderful job in creating meshes with homogeneous or adaptive triangulation.
It contains a comprehensive set of tools to optimize and prepare STL files for 3D printing, such as hollowing and support generation.
Cons
The remeshing tool needs to be faster, as in some cases it takes up to a day of waiting time.
The sculpting tools need the addition of a proper brush for creating sharp creases and ridges.
The standard shape library is rather limited. It would be nice to have this connected to online repositories such as Thingiverse, MyMiniFactory, or Cults3D.
Most Important Features
STL file repair
Remeshing
File conversion
Return on Investment
It speeds up projects by streamlining the CAD-to-3D-printing workflow
As an advanced user, I have written a few tutorials about it as well