VariCad is the most expensive of them, but it has been quite nice, and I wish open source items were as good :/. But maybe FreeCAD will get there. VariCAD has evaluation licenses available, as well as does MeshCAM. While MeshCAM is a Windows application, it works fine via Wine (actually the site has instructions on how to do it, though it doesn't really need them). I'm leaning up towards paying for that one as well..