In no particular order...

I use Hexagon a bit, learning Blender, for mesh and texturing.

I use Carrara for outdoor scenes. It's render engine needs some love, but the program accesses both Poser runtimes and DS libraries directly, making scene creation within Carrara with full figure functionality a possibility. It also allows networking of single frames with bucket distribution. If Poser brought in instancing I'd probably drop Carrara.

Photoshop for post work.

I have Studio, only for the library for Carrara. I don't use the program itself.

Within Poser, Snarly's EZSkin and Scene Fixer get the most use. Another script I use is called 'snap to' and it is AWESOME! I do big scenes, so if my camera is 1000 units away from centre and I bring in a prop I want in a character's hand, prop loads at 0,0,0, I hit 'snap to' in my script library, click on character's hand, and 'BING!" the prop appears in the hand. Still need to fine tune position, BUT IT'S THERE!. I use it quite a bit now that I have it.