Depends on what data.
I have several backup servers at home, all powered by Raspberry Pis. They are attached to ZFS storage pools, with ZFS snapshots and additional backups across servers (i.e. they are backing up each other).
For backing up my end-user devices to the backup servers, I exclusively use Borg.
For not the most private data, I use mainly MEGA, but theoretically you could use any cloud, especially when using something like Cryptomator in conjunction with it. However, I consider MEGA having the best commercial general cloud service on the entire earth.
I also use Nextcloud, but that is mainly for its extended functions, like WebDAV, App and Backup integrations in other Android Apps, allowing to back up to Nextcloud, etc. and not for pure and plain boring data storage.
That said, I would strongly recommend against using SkyDrive (i.e. OneDrive), Google Drive or the like for obvious reasons. Even if the data is encrypted. Google is so rich, I am entirely sure they could break any commonly used encryption, if they wanted to use their computing power for it.