I have never tried Anya but I met her on my way out from seeing Katie. She looks pretty and probably a bit trimmer than Katie at the moment. Not that Katie is big but she isn't quite as trim as she was four or five year's ago.
That said, Katie always gives a good service and she is very friendly and amenable. As it is, they are sisters and they are sharing a flat. You could always book to see one after the other. You never know, they might even be open to you seeing them both together.