A lot of content creators on Renderosity use Blender, but I think there's a lot who use 3dsmax or Cinema4D, and some that use Hexagon and Carrara as well.  I think the most commonly used app among them all is going to be Zbrush.  Almost every time I read a featured vendor on this site, and they are asked about their software of choice, Zbrush plays a part in the workflow somehow.  Same in most professional pipelines, if you read 3dWorld or 3dArtist mags.   I know a couple of the big architectural and scene builders for Poser use 3dsmax.  For example, DreamlandModels, and of course, Stonemason.

I'd suggest definitely investing in Zbrush if you can.  That app is wildly popular with professionals in every category of pipeline workflows.  I think Teyon makes all his characters in there, and doesn't even utilize a standard poly modelling software.

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Tools :  3dsmax 2015, Daz Studio 4.6, PoserPro 2012, Blender v2.74

System: Pentium QuadCore i7, under Win 8, GeForce GTX 780 / 2GB GPU.