The Doctor himself:
So far as I can find, there are no M3 or M4 morph + clothing sets specifically for The Doctor himself, that are worth having. There’s a really rather ugly “Tom Baker” set for M3, and one “David Tennant” for M4 that looks nothing like Tennant, and frankly neither is worth having. [Update, May 2017: I found a fairly good Tennant face for M3]. You’d probably do better by trying to make your own, either with M4 for Poser or Genesis 2 for DAZ Studio.
There are of course a vast number of choices for clothing for young companions, but Dresscoat Italia for V3 has the right amount of “1970s” in it for a retro Pertwee or Baker-era Doctor Who render…
Your first stop for a new Dalek Empire should be Mechmaster who has a range of superb Daleks for Poser…
SamTherapy’s free Exterminate 2012 collection is… “A truly massive update to my Dalek builds. All canon Daleks rebuilt, 5 new canon Daleks, 4 new non canon Daleks. All models have ERC. Should work in any version of Poser from 6 upwards. Not tested in DAZ Studio.”
There’s also Dystopia Productions which has some nicely modelled P4 and P5 daleks…
Xantor created a free Davos for Poser.
More old enemies, for recreating lost episodes from the 1960s and 70s, are available from Orange Cow who has some cool old monsters for Poser, including some vintage Cybermen, an Ice Warrior, and a Yeti.
I’ve seen one good DAZ/Poser render of a Sontaran, but can’t find any links to the model online.
A TARDIS for Poser…
The Sonic Screwdriver:
Suitable sci-fi sets:
There are also vast numbers of generic sci-fi corridors available as 3D models, including some nice ones from Stonemason, but I didn’t see anything that especially said “Doctor Who” to me.
Of course there’s also the free Doctor Who items on Google 3D Warehouse, although not as many as you might expect. The modelling there is often rough, the textures almost always awful, and you’ll have to export from Sketchup to OBJ and from there to DAZ or Poser. But there are a few quality models there such as nice Tardis Monitor screen 2010, and some rare TARDIS interiors if you really need one from a particular era.
Carrara 8 is DAZ Studio's official 'big sister' software.
Carrara loads all DAZ and Poser characters and scenes,
and supports LuxRender for top-quality realistic rendering.