Rclone + its encryption + Google Drive business account is the best option I've seen so far. Unlimited for $10/month since they don't enforce limits on single user accounts yet.
Some alternatives I see here and the reason I don't use them:
SpiderOak: I've written extensively about this [0]. TL;DR: It's slow as hell and they're utterly unmotivated to fix it. It's slow enough that I consider it unusable. Fine for one off documents, nothing else.
Syncthing/Resilio/Nextcloud: I'd have to provide my own storage.
Dropbox/AWS/GCP/Azure/Tarsnap/Rsync.net: Too expensive.
Some alternatives I see here and the reason I don't use them:
SpiderOak: I've written extensively about this [0]. TL;DR: It's slow as hell and they're utterly unmotivated to fix it. It's slow enough that I consider it unusable. Fine for one off documents, nothing else.
Syncthing/Resilio/Nextcloud: I'd have to provide my own storage.
Dropbox/AWS/GCP/Azure/Tarsnap/Rsync.net: Too expensive.
[0]: https://news.ycombinator.com/item?id=13306353