I don't own any of those packages(well, I do have Blender but I can't use it, such a convoluted UI that I've never managed to work out), I find that TG will usually be the final app' I use for output so the other softwares actually all need to fit in with that, instead of the other way around, I simply could not do most of the stuff I can do with TG in any other application, so powerful is it, full stop.
I don't see TG as being a program that I need to export much from, since the functionality and the renderer is so good. This would only be the point of view of the simple hobbyist renderer that I am, though.
I do understand that many others need to set up a workflow that passes between packages easily to fit into their ways of working.
I voted 'other'. Because, my needs are basically to get things into Terragen with as little effort as is possible.
The softwares I use for this would be chiefly; Carrara>>Poseray>>TG. In that order. While Carrara isn't usually listed in things like this, being a somewhat minor used application on the whole, it's an extremely powerful application, with many great features, like particle/hair/volumetric simulators, animation capabilities and also a fantastic renderer, with many extra features than other packages I've used or trialled has/has not. All that it's missing is TG2's procedurals, in fact, in my opinion.
I realize you're probably looking here mostly for users who would use these big-end app's in an integrated commercial pipeline but here's just my tuppence worth as a TG hobbyist enthusiast. Hope it's not deemed as useless input.
*Edit: After TG has finished its work, I'll use PS for any post-work that's required.(just saw Lane's post below and thought it best to add it here, too)
