Hi KenThere are quite a few that use 3dCoat.
Myself vidi planetstardragon bluemidget to name a few that spring to mind.
It is a good programme for sculpting/modelling and is easier to use than zbrush I feel.
The downside for you would be that it is only a modelling programme yes you should be able to
take it into substance but to use it as an Avatar within ic5 and 6 when launched it would need to be rigged to a skeleton.
So you might be better looking at MayaLT. I think this is approx. $800 but at least you could rig etc and I believe substance also supports it as well as max.
The reason for saying the LT version of Maya is because it is considerably cheaper than the full version which is 1000's of $ as is 3ds Max.
Another option would be to use 3dCoat and then rig your model inside Daz3d which vidi does very well or pay Mixamo to rig it for you on their site.
Edit - Just thought you could also try Blender for rigging a Character as Blender is free. Also would be useful for creating props buildings etc only downside with Blender I find the UI a nightmare. But Free is a nice word perhaps try it and then decide.
Hope this information helps in some way.