Yea, I have to agree with GA... Bryce is limited, but you can import the objects you make in alot of the programs he mentioned. Bryce is more of a landscape type program like Terragen (which I'm sure it is) and Terra Former. 3Ds Max or Autocad would be your best bet on making some 3D objects. But if you want to put them in a scene, Bryce is good for that. I think I explained that pretty well. Correct me if I'm wrong people
Lightwave is also popular. Maya is slightly advance and usually used mostly with movies, Cinema 4D (Haven't messed with). There are a whole bunch of 3D progs out there. I hope this helped a little.