The simple answer is, any that output .obj, .lwo
.FBX is coming at some point.
TG also excepts object sequences.
I use Maya, others 3Dmax. Lightwave is popular here. And Blender (free) is often mentioned too.
Lots of people also use modeling specific software like like Modo, or wings3D (free) and Speedtree and xfrog for plants
As far as TG is concerned, it does not mater so long as your trying to import the model as an .obj IT works fine, and most obj questions have an answer in the forums. Just about every obj problem you can have has been addressed by now in some way. So you can be confident that whatever issues you may run into, you'll be able to resolve it.