For hosting common files it's ok. Also it is on Android too do, great to transfer files between your Windows and your phone. But if you want better security you have to subscribe a monthly offer.
Dropbox - Online Sync and File Sharing
Serv-U Managed File Transfer Server - Comprehensive security, automation, and control over file transfers in and outside your organization
Google Drive - Access and sync your files anywhere
SSHDroid - Download SSHDroid app for Android. Connect through SSH to your device!. .
Mega - Secure File Storage and collaboration
zFTPServer Suite - zFTPServer Suite is a user friendly and easy to use FTP server.