As others have already said, Carrara is more of a general 3D application. It includes several tools that DS doesn’t have, and tools that Bryce doesn’t have. I’m not a Bryce user, so I can’t really give a good comparison between Carrara and Bryce, but I get the general sense that the landscape tools in Carrara aren’t quite as robust as Bryce. That being said, I’ve seen some fantastic landscape work done in Carrara, Howie Farkes (http://www.daz3d.com/shop/catalogsearch/result/?q=HowieFarkes) has some beautiful outdoor scenes for sale here that rival work done in Bryce or Vue.
I’m a long time Carrara user (since version 2), so I’m probably a bit biased toward Carrara. I find the posing in Carrara to be just as easy (maybe a bit easier) as in DS, and the 8.5 beta handles Genesis quite well. I also find materials and lighting to be much easier in Carrara. The dynamic hair in Carrara isn’t quite ready for “prime time” for animation, but is fantastic for still images (much better than the standard trans-mapped hair). Carrara also has modeling tools that are quite good, there are several Carrara artists that do a great deal of modeling in Carrara. Carrara also has dynamics, but doesn’t support dynamic cloth like Optitex in DS, or Poser dynamic cloth. Carrara is faster at rendering than DS, though DS 4.5 is getting better in the speed department.
Carrara also has a tree creation tool and replication/instancing, spline modeling, displacement painting, and several others tools that I’m sure I have forgotten. Lighting in Carrara is very easy (at least for me), and setting up reflections, and caustics is quite easy. Materials in Carrara are quite powerful, and for me are a lot easier to wrap my head around than doing advanced materials work in DS.
If you are looking to expand your tool set, and retain the ease of use of DAZ/Poser content, right now for price/performance Carrara is the best tool available (C4D and Interposer Pro is another option, but is a lot more expensive). Because Carrara is a more complex and feature rich software than DS, it also comes with a greater learning curve. But, a lot of what you learn in Carrara can be easily transferred later if you decide to move on to an even more feature rich 3D software.
I realize time is limited due to the sale time frame, but there is a trial version of Carrara available that could help you make a decision. PhilW has some very good training videos available here that would help speed up the learning curve a great deal. There definitely isn’t a make art button in Carrara, but I still find it easier to get decent images from Carrara than DS. If you willing to roll up your sleeves and invest a bit of time getting to know Carrara, then I would strongly recommend getting it. I’m pretty comfortable with DS now, but I still prefer Carrara.
Hope this help, if you have any specific questions, feel free to ask and I’ll do my best to respond quickly. I really enjoy using Carrara,