Dropbox - Online Sync and File Sharing
Sync.com - Sync. com offers a backup tool and a file sharing service, rolled into one.
Mega - Secure File Storage and collaboration
Zoho WorkDrive - File storage & content collaboration tool for modern teams
ownCloud - ownCloud is an open source project enabling businesses to host their own cloud storage while maintaining regulatory and compliance needs.
kDrive - The most privacy-friendly online storage and file sync service. From 2 TB, hosted in Switzerland.