The weak points of both ZBrush ZRemesher and 3D-Coat Autopo are:
• They’re not very good at hard-surface retopology, especially when there are infinitely sharp edges present in the model, like after Boolean operations.
• Small details are often lost, mangled or cause topology deviations.
• Thin parts often result in bad retopo / retopo issues like holes.
• 3D-Coat Autopo sometimes generates singularities where more than five edges converge, resulting in surface tension and subdivision artifacts.
• The topology flow is not always ideal. Often there’s a bit of a polygon flow shift along concave and convex edges / ridges, causing slightly diagonal polygon flow where edge loops and poly loops should accurately follow creases etc…
An area that would be ideal for machine learning is recognition of shapes, such as faces, and applying an optimized retopology to that.
Have a look at this thread as well.
And here’s a great site about topology.
If you’d need a tester for a new tool, I’m interested. 