After using Wings3d for... 20+ years at least. Looks like development has just about stalled... Shame. Great modeler, so fast, so weird-just the way I like it. Good time for a bit of new learning though.
Spent some time in Blender, and it seems great for art but not for CAD.
FreeCAD seems pretty good though. Parametric, lots of CAD features, and after some testing I think it'll work well.
Lots of great paid tools, Fusion360, Rhino3d, Google Sketchup, etc... But FOSS needs support and serious users.