CAD and 3DStudio Max are the most demanded for work. So I suppose it's good to learn them, and once they hire you you just can use what you want.

For modeling for Poser the best is Hexagon. Some people also use Shade.

Don't use a free modeler. It may seem easy at the beginning and zero price, but they are free because they produce meshes with lots of problems for render. If it's just for your use, it's ok, but don't sell things made with free modelers. They are free because they are worse.

I took a lot of time and errors to learn this. In the past I used Anim8or and Art of Illusion. They were great for virtual worlds in VRML, but a pain for Poser.

Hexagon works great as a modeler in general, and has the tools to make flawless meshes for Poser.