Google Drive, Box.com is the tool that I use. Now Box.com has become more useful by adding a new feature that allows you to create and edit PowerPoint, Word, and Excel files within your Box account. Box is also supporting the use of Google Drive to create documents and spreadsheets through your Box account.
Applications for Education
If you or your students prefer PowerPoint or Word to Google Documents or Google Slides, Box.com could be a good option for you to use create and share your work online.