Ease of use depends on you mostly but I can say with some confidence that modeling in Rhino is fairly easy. However, it's only a nurbs modeling program and doesn't allow for decent poly modeling. Of the three you mention, C4D would probably be a little less intimidating and thus, easier for you to come to terms with quickly if you want to work with polys. Max is powerful, and great with polys but its interface is lacking and if all you want to do is model, it has too large a price hit. For my ease of use in nurbs modeling I'd say Rhino is the way to go but for polygon modleing, of the three listed, C4D may be easier for you. If you can afford Max, you may want to consider Lightwave instead, it's one of the best poly modeling programs around.