I've used 3DS myself, it's a pretty good program, very useful in creating clear and vivid models. I mostly use it for 3D worlds and Car models, nothing too amazing. Blender is also very useful, but takes a while to get used to the interface, it is a strange interface indeed because besides being a 3D modeler it's also a 3D Game Designing engine. Milkshape, which I've seen is very seldom used, is geared more towards low-polygon models, but i've found it very useful in creating precise models of animals, people, and really small things, plus it has plugins to import 3DS, Maya, and from other modeler apps.
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