I don't think there are too many people in the world who have a thorough knowledge of all educational systems in USA, Canada and Australia. Particularly USA and Canada, every state and every province is so different. It is difficult to say if education in Canada is better than that in China. In Canada, the focus is not on foundation education,i.e. math and literacy skills. Instead, the teachers here teach our kids how to develop their potentials. Whether you will like it or not depends on you. Lots of Chinese immigrants in Canada keep sending their kids to tuition school because they are not used to the system here. I would say the early the better, because your 6 year old daughter will pick up English very soon. If you wait till she is 12 to come, English will become a barrier for her.