sadly i will never be able to afford what is commonly considered a real piece of art software. I used bryce from Version4. It is easy to learn and somewhat powerfull. There are things that bryce does for you that the pro programs ask you to take care of. More control but more work and a higher curve. 
 I love the render in Carrara yet there is sonmething about the atmos in Bryce.
 Lol, i never do understand why it matters what you use, as long as what you end up with is good product............