DS4 (occasionally poserpro 2010)

Modelling, rendering, particles, VFX etc in XSI.

Sculpting/texturing with ZBrush though i'm saving money to get mudbox.

Compositing I use photoshop.

For stills I pose in DS/PP, import as OBJ into XSI and then build the rest of the scene around that as needed there. For scenes which need characters interacting with custom built props, I model them in XSI, import into DS/PP, and pose the character around them. Then export the character as usual.

Don't do a lot of anim work but the few i've done have been animated by exporting as COLLADA and importing the rigged character(s) in XSI and working on them there. Takes longer to setup but IMO much easier then trying to animate in Poser/DS itself...