I'd love brushables of Gallus, Terramar, and Rumble. I'd also add Silverstream, but I just found out that apparently she is getting a toy. (So, yay to that!)
Most importantly: a brushable Minuette! (Seriously, she's been around since the first season and still doesn't have a brushable!)
Also, lots more hippogriffs!!! Other than that one Skystar brushable, I don't think they've released any hippogriffs?