I use both Poser and DS (Carrara as well). There are some things Poser does better, and some things that DS does better, and features in each that the other does not have. But for the most part, your preference between the two is predicated on your needs, interests, and which interface works most closely with the way you think.

It's very easy when you start with 3D to think that the grass is greener on the other side. It's also very common to feel that "free" software isn't as good, or as easy to use, as software you pay for. But DS is a very capable piece of software for using and rendering premade 3D content. There is a rather large learning curve when you first begin to use 3D software, and the recommendations you have been given regarding learning DS first are very sound. It will give you a chance to learn the basics, and decide if you are really interested in putting forth the effort to learn to create 3D art. As you learn more about 3D, you may decide that you want to explore Poser, or that Poser has features that you really want to use.

For example, Poser has the cloth room which will enable you to make your own dynamic clothing (requires modeling and other skills as well). Something that you can't really do in DS (though there is a bit of a hack), but you can use premade dynamic clothing designed specifically for use in DS. Dynamic hair is a feature included in Poser, but there are two Dynamic Hair plugins available for DS at very reasonable prices.

The render engine in DS, 3Delight, has been used for rendering animation and special effects for Hollywood films (i.e. Happy Feet Two, Resident Evil, etc.), but some of the great FX rendeing functions aren't easily used in DS. Poser uses Firefly, which is only in Poser, but is a very capable renderer, and seems to be a bit faster than 3Delight in DS (though you can export your scene from DS and use the free stand alone version and rendeing is faster). The one area where Poser falls short is that firefly doesn't support caustics, which can make getting realistic glass, water, crystals, etc. very difficult (3Delight does). Of course, if you need caustics, or an unbiased render engine, Poser has plugins for LuxRender and Octane Render (DS has plugins for these as well).

I find using DS a bit easier than Poser, and lighting is much easier for me in DS than in Poser (but Carrara beats both hands down for me - your milage may vary). I own every vesion of Poser starting with Poser 2, but have only really been using DS since DS3. I find getting renders I am happy with much easier with DS than with Poser, but others have the opposite experience.

I hope all this makes some sense, basically a lot of what you find/feel is best from software to figures to other content is really a matter of personal preference. Welcome to your new hobby and the often ambiguous world of 3D. 

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