What feature do you want to see added?

I was thinking that it would be useful to introduce other file storage services, such as iCloud Drive and Mega (at the moment only these two come to mind) to help Minecraft server owners avoid spending money on subscriptions that they would otherwise only use for backup of their server.

Are there any alternatives?

Nope.

Mega doesn't have a native library for Java and doesn't have documentation for a generic HTTP API if they have one.
iCloud does have a native java library so we'll look into it further.