Lets see. Silo: An excellent subdiv modeler but a bit lacking in key features (illustrator import, spline modeling, etc) Overall I'd say that it is a GREAT piece of software. Wings3d: For free its great. But I've always found it limiting in its modeling workflow. I like the concept of manipulators and of icons for functions used often. Icons work well in conjunction with shortcuts and shouldn't be eliminated all together. That said for free it can't be beat. Hexagon: Probally the easiest to pick up. At least it was for me and its very powerful. The replicating functions and dynamic geometry make it very flexible. If I had to choose between the three I'd pick Hexagon. Another excellent modeler that should be mentioned here is Modo. It will likely be my next purchase. Its flexible interface, macros, and scripting functions make it a versatile tool. Plus the addition of rendering and texturing tools bring it up a notch in my book. I'll likely keep Hexagon in my toolset as it does a lot of things faster then other programs I've used. And of course Carrara's speedy rendering and other features will keep me using it for a long long time.