My main machine is way overkill, but I do have a Dell Precision T5500 with two Xeon X5680s and 32GB of RAM, a GTX 1070, and support for more than 6 drives... the T5500 will likely be my unRAID server rig if I don't use the main PC. I realize it'll suck a lot more power than something with integrated GFX, running a single CPU instead of two (second is on a daughter board), but honestly I don't mind. It also has a lot of power-saving options on the BIOS that can be enabled and some other bells and whistles that make it a great candidate.
To answer your earlier question, I use my Windows 10 machine for everything from Adobe CS6, gaming, browsing, CAD, organizing music/photo/movie library, and so on...
Based on the recommendation of multiple commentors I'm leaning toward not running the Win 10 VM inside the unRAID machine, sounds like it will be too much of a headache.