I like https://www.borgbackup.org/ and you can get a relatively cheap storage plan on rsync.net just for Borg (https://www.rsync.net/products/borg.html)
Retrieving backups is a little manual. Perhaps someone has created a nice GUI for it.
There are at least two GUI's for borgbackup:
* Vorta (https://github.com/borgbase/vorta)
* Pika Backup for Gnome (https://apps.gnome.org/app/org.gnome.World.PikaBackup/)
Vorta is multiplatform and more reliable by my experience.