3DS is by far the best but not the easiest to use. I usually use it for complete scenes and Mya for individual components to a build. Motion Builder, Z Brush and Mud box are also good apps to have access to. I love Z Brush for terrain meshes and its very easy to do however, I get better terrains using MudBox. Something else to look into is Unity 3D for your live environments. Easy to import, light and animate and particles are pretty much a no brainer there.
Here is a scene I created in 3DS that is now live in a virtual world.
