Actually DAZ Studio itself is free.  They do charge for plug-ins, but if all you want to do
is pose the model and then render it in Maya, DAZ Studio should be sufficient for that.
Poser as it comes out of the box offers goodies like a more advanced material room,
a cloth room for draping clothing props over the model, a hair room for creating hair,
and a set-up room for converting an object into a posable figure.  As far as I know,
DAZ Studio doesn't have these with the free version.
They both come with free figures. Poser has a wider selection though. If you are
looking for realism, you will probably need to buy the model separately.
Poser's latest models are Simon G2 and Sidney G2
Poser 7 comes with some Kozaburo hair models, as well as you being able to
create hair in the hair room.  With DAZ Studio you are limited to prop hair
and for something nice you have to buy it separately.