If there were other air forms around that I had to fight, then I might prefer falcon. Sucks not being able to flee when you engage someone at high-altitude. Also, from what I hear, there are some places that the "big" birds (i.e. eagle) can't fly into/outof that the smaller ones can. If that's true, then that's another advantage to the small ones. It's not like he's fighting anybody *in* the eagle form- he just shifts to tiger.
I'm curious what some of the newer ones are like. Mantis? Not sure if there are others.