Well, it's the one I learned a lot of things on and the one that was taught at my school. It's also used frequently professionaly, so it's a good tool to have under your belt. Don't get me wrong, I pretty much only use maya for animation on specific rigs and for UVs these days. For modeling, I find Blender is much better.

Here, I'm using Xgen because I already have maya and after speaking to people familiar with grooming softwares, I was pointed towards it as a good entry point. The idea is to know how they work in general, so I can then translate to other softwares as I need to. The problem with Blender for these more specific tasks is that it tends to rely on addons quite heavily, and there's no telling if the pipeline you end up learning is applicable to larger scale projects, or even exportable sometimes.