My kids have gone through the Catholic school board system in two provinces. When they started in Alberta, (2012ish) the school board accepted all faiths at the grade school level. Parents had to acknowledge that the curriculum was faith based (which really only meant that they talked about God, and started the day with prayers). Specific activities directly linked to Catholic rights, (mass, baptism/communion preparation, etc) were optional for non-Catholic students if the parents signed a form. Those kids would have alternate activities for those times. To enter the Catholic High school, children were considered old enough to make a choice about their faith, and had to choose to undergo the appropriate religious rights in order to be accepted to the school.
When we moved back to Ontario in 2015, we were surprised by the strictness to get accepted to the Catholic schools. At least one parent had to have been raised in the Catholic faith, and in theory a practicing Catholic. We had to agree to have the children baptized, go through confirmation, and partake in first communion. There were also no exemptions to participate Catholic specific activities, all children were expected to attend mass and religious rights preparation classes. There was also a mandatory religious class all through grade school, middle school, and even one semester each year of high school. Both systems also required uniforms for students in middle and high school. This was the same in both cities we lived in.
I will agree that the quality of the education available in all three cities they went to school was better in the Catholic schools. Smaller class sizes (20-30 students), better student-teacher rations, and I believe more access to IT, career counselling, special needs, non-sports related clubs, etc. The biggest drawback was due to the smaller student populations, the sports teams had difficulty competing in team sports.
For me personally, I was able to overlook the religious aspects of the schooling, which did have some benefits in making them better people and understanding different cultures.
I'm also not saying that public schools or charter schools are bad. Just in the areas I have lived, the Catholic system offered more. If I were to do it all again, I might consider sending them to French schools, at least until high school, to give them even more of a leg up.