IMHO, both Carrara and DAZ Studio (DS) are very good alternatives to Poser. Each program has it's strengths and weaknesses. It really just depends on what you want to do (I have all three).

I didn't use DS much other than to just play with it until 3 came out. I got DS 3 Advanced because it had the 64bit option. I'm quite glad I did. It's very responsive, much faster rendering than  before, and has some nice features like the Morph Follower and UberEnvironment lighting. I'm not a lighting expert in DS, but I think this image came out pretty good using UberEnvironment (also used morph follower):
http://www.renderosity.com/mod/gallery/index.php?image_id=1994089

I've had Carrara since version 2, and really do like it. Version 8 will be fully 64bit. I'm playing with the 64bit Beta now, and it's great! It allows you to do things that are very difficult, or impossible in 32bit. There are occasional problems with Poser content in Carrara (and DS), but for the most part everything works very well. Carrara gives you a lot more room to grow than either Poser or DS, and has a faster render engine. My render preference is Carrara first, then DS3A, then Poser. Poser is quite capable of doing top notch renders, but I've never been able to get good lighting as easily as I can with Carrara.

Materials usually need to be tweaked in Carrara or DS, unless the item has Carrara or DS specific shaders. It's a fairly simple process though, and you can get some very nice results. The materials for the car in the image at the link below were done with stock Carrara shaders with some minor changes, to replace the Poser shaders that looked very unrealistic in Carrara.
http://www.renderosity.com/mod/gallery/index.php?image_id=2009629

Carrara does landscapes, quite well, but possibly not as well as Vue (don't have Vue to compare). this link below will give you an idea regarding what Carrara can do with "small scale" landscapes.
http://www.renderosity.com/mod/gallery/index.php?image_id=1832144

Like others have said, give both DS and Carrara a test drive. Often with 3D software what "feels" right is the best tool to use, because you will enjoy using it!

Good Luck!
DR

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