I'll second Mazak, Cinema4D rules! I have Hex2, but I find it painful to model anything with it, but many love it and it creates very nice and complex models. You can also get Silo2, which is very cheap and powerful, but it doesn't do nurbs, only polygon and subdivisions. Or try the free Wings3d, same kind of modeller than Silo, but the poly count can be a big stability issue.