I agree with the curious wolvar pup. That would be a good choice.
I ended up using mine on on a Kun Lai runt because I wanted the 4/14 id and I could only find him in poor quality and was tired of farming him.
It probably wont be your last Flawless Humanoid Stone, so you don't have to panic about making a wrong choice. Also, I have stashed some in my bank for later. No need to spend it as soon as you get it.
Grats on the stone btw.