In summation, all three of these cloud-based servers offer valuable resources for both educators and students. There are paid resources, like Microsoft, and also free resources, or those with little to no cost, like Google. It is up to the school district or principle to decide which system will be implemented, and is best for their learners. It is important to keep in mind the budget of the school and grants that are available to support technology in the classroom. 

Here are some useful links to decide which system will work best for you: 

https://www.microsoft.com/en-ca/

https://education.microsoft.com/en-us

https://blogs.windows.com/windowsexperience/2017/05/02/microsoft-education-empowering-students-teachers-today-create-world-tomorrow/

https://products.office.com/en-ca/microsoft-teams/group-chat-software

https://www.apple.com/ca/education/apple-teacher/

https://www.apple.com/ca/education/products/

https://www.apple.com/ca/education/teaching-tools/

https://www.apple.com/ca/education/teacher-resources/

https://teachercenter.withgoogle.com/

https://www.google.ca/docs/about/