Can only speak from experience ... as a user of both Carrara 5.1 (standard) and a more recent user of Vue 5 Esprit, I've found that the packages are complimentary. Carrara is the better all-rounder, and definitely the faster and higher quality renderer on the whole. But Vue has a clear edge for environmentals and landscapes.

Depends what kind of work you want to do - for me, lighting is the key for my style of work. I tend to focus more on overall visual impact, and work with simple models and geometry, rather than complex modelling and shading. Carrara comes out a clear winner for this.

The overall render quality seems higher in Carrara e.g the smoothness of volumetric light at lower quality settings, soft shadows are much smoother, anti-aliasing is clearly better in Carrara esp when viewing object edges in volumetric light, you have more control over rendering parameters in Carrara (unless you go for Vue Infinite perhaps).

Vue creates excellent water (using fractal terrains) - even better if you get Vue Infinite and get the Open Ocean functions.

Carrara is generally pretty robust and dead easy to learn, but has a number of annoying bugs e.g. doesn't replicate the visiblevolumetric properties when you replicate a light using the particle or replicator functions. But Vue seems to crash randomly - might be my GeForce 6800 OpenGL Drivers.

Vue definitely has a future - does Carrara have a future after being bought by DAZ? Remains to be seen!

That's my tuppence worth! Almost all the art on my blog (http://craftycurate.blogs.com/) was done with Carrara if that's any help!

Thanks
Richard