I am using 3D Studio Max (once a year =) ... after few tutorials you can get into it...

But I remember that when I was about 13 me and my friends we played with some aplication called 3D "something" and it was part of Corel package (dont remember name of it).

That was realy good and simple but I think they don't offer this application anymore.

And Bryce 3D was simple ... mainly on terrains but could do anything with it..