I found ViaCAD quite easy to use and learn. I struggled with bugs in earlier versions of FreeCAD, but I have heard it is much better. Fusion360 is a little difficult for me to use, but its extremely powerful and able to do things neither of the others I mentioned can do. Fusion360 has built in CAM capabilities with some very good HSM capabilities as well, but also has a little bit of a learning curve. I did have to modify the post processor for Mach 3. I still do most of my 3D CAD in ViaCAD. Its also got very powerful 2D CAD capability, but because most of my 2D is supplemental to 3D and mostly for help with CAM I tened to do most of the 2D stuff in CamBam.