To be honest, I do not know the answer to your question in terms of School rankings. But since I was a student in Canada, I can say that the school's performance may vary every year, depending on its leadership, funding etc. Yes you can take the Fraser Institute Rankings information, but once you narrow your choice of schools to, let's say 3 schools; do your best FBI research. Look for the good and for the bad as it it always good to see things from more perspectives, especially when it comes to your children's education. (But remember you can usually change schools as long as you move close to them)
For more detailed info you can get Pre-arrival help before arriving in Canada to arrive prepared. These services are free ( payed by the Canadian government) Hence the list on IRCC website. Check them out at
http://www.cic.gc.ca/english/newcomers/before-services.asp
For general help you can check out http://nextstopcanada.ca/ . It is the only general settlement service for people who are not in Canada yet and you will find it at the end of the IRCC list I just provided for you. But Check the list. See what will be best for you.
Best of luck!
