Nendo is easy and great for organics
Izware Nendo (who owns it now) offers the app for $49
Compared to Sketchup which free - no comparison. However as a subdivisional surface modeler, I think Nendo is great.
No other 3D modeling app gives me as much freedom to create organic models, animals, plants, monsters - the smooth capability after you model at a lower number of faces creates smooth and rounded shapes with great success.
Really I'd use Nendo to create my complex shapes and models then import to a more complete rendering application like Sketchup. 8)