It really depends on the type of skiier she is. What are you looking for. How and where do you ski? I prefer the features of the Tyrolia series of bindings, but understand that, IMO, it permits a degree of safety that some other bindings don't provide. Having said that, I've had remarkable luck with Salomon and Marker bindings as well.
My advice is to do your homework. Find a good shop and ask their opinion as well, but be certain you can articulate your skiing style, perferences and habits.
Hope it helps. Good luck.