I guess not a lot of people in this forum will suggest Bryce :-) I would say: try the demos. Bruce is more or less specialised in landscapes, but C4 has been upgraded in that department. Maybe you can compare the work in the Carrara and the Bryce galleries here on Renderosity, to see what kind of work people use it for. Carrara's rendering tends to be faster too. And the moddeling in Bryce is not great. I would recommend Carrara greatly, but as I said, this is not the most objective forum for that question.