We support Dropbox and Google Drive. We’re considering Email, Box and Microsoft OneDrive as the next backup services. If you have other suggestions, let us know in the VIP forums.
I would also like to suggest Nextcloud as a option. I will probably temporarily enable google drive for now, but my main cloud solution is Nextcloud and I would prefer to back it up there instead.
I looked into this briefly and it seems like we’d need to know the url, username, and password to upload files. Is is standard to provide the username and password like this for Nextcloud via WebDAV?