Carrara is brilliant, I've used it since v5, which you can probably find the complete Pro version still online, they released it freely a couple of years back. Of course, you wouldn't have all the newer features then, hard/soft body physics, new volumetric cloud/fire/fog engine, new ocean primitives, displacement(slowish but works very well on any surface) wind, etc. It's so easy to use, unlike Blender, which I have but never ever got used to, or even liked actually, I have heard and seen great things that others have done with it, though.
I would definitely go for Carrara, it does everything, is super-fast(both UI and the ray-tracer), the animation is fantastic to use. The only part that has never impressed me is the built in plant creator/editor, the realism just isn't there, a shame, there are tons of other plant softwares that I'd much rather use.