I only had enough money to buy one figure today, so I was tied between Grievous and Aurra. Eventually chose Grievous since he had more accessories and what-not.
No other TCW waves past this one have shown up so far - hope to see them soon.
Viszla is the most popular by far, I haven't seen him at all. Next I would say is Grievous, then Aurra Sing, then Mando Guard. I'm shocked Aurra isn't one of the first to go, especially because she's such a cool character and well-done figure. If anything, there's an over-abundance of her.