The free stuff I have played around with:
Blender
Sketchup
BRL-CAD
Creo Elements
FreeCAD
123D Design

Day to day I use Catia, Powershape, Geomagic Design and Moi3D. Even simple software like Moi3D blows the free stuff out of the water. And I don't get this culture of paying for a slicer but not for a modelling program. Its like playing a £10 guitar through a £1000 amp... makes no sense...