“Unlimited storage” with a “fair use” policy are a bit problematic. From the Jottacloud terms of service:
Although Jottacloud does not limit bandwidth or storage on Unlimited subscription plans, we reserve the right to limit excessive use and abuse of the Service. If a user’s total storage and network usage greatly exceeds the normal usage of an average Jottacloud user, and/or indicates that the Service is being uses for other than normal individual and non-commercial use, this may be deemed as abuse of the Service.
In these abovementioned cases, we reserve the right to offer an alternative Jottacloud subscription, cancel the subscription, or in some cases delete the user account and/or user data. The user will be contacted by us with a suggested solution or notice of action in such events.
Everything will be fine until at some point, too many people do excessively use their account and their business becomes unprofitable. Then they will either block your account or charge you more. You will have a new “Crashplan experience”. Sure, for some time, you get a good price. But don’t expect it to work forever.
And take into account the time to re-upload 10 TB of data. If they cancel your account, one month may not even be enough to download the data.
Also one thing to consider is speed: Do they guarantee something? In the case when your server crashed and you need to download the 10 TB backup, what will be the speed? Often, downloading the first GB is fast, but then they will slow you down. “Excessive use!”. Then you wait several weeks until your backup is restored? Don’t complain, you just get what you paid for.
So, if you don’t care about the hassle, go for “unlimited storage”. But if you rely on your backup and it is important to you, better choose a provider with profitable prices.
For 47,48 € (currently 52,98 USD) per month, this German data center provides you with 10 TB either as a “storage box” (webDav, FTP, Samba, …) or nextcloud:
https://www.hetzner.com/storage/nextcloud
https://www.hetzner.com/storage/storage-box