Other content, private but not sensitive, like holidays photos, can be stored and decrypted remotely and it's a good practice to use encrypted partitions by default. I don't believe Hetzner would do any of the grey things that Google, Facebook and now Apple are doing (i.e. actively scanning your data for advertising and other purposes), but there is a practical problem of broken hard drives - it doesn't matter if it breaks in your place or at a hosting provider, you have a hard drive that is broken but you can't remove your data from easily, but someone else might. I estimate the probability is extremely low, but there is very little downside and effort required to encrypt data partitions nowadays, so I don't see why I shouldn't do that.
As for the interception of data in transit, nowadays everybody is using TLS for everything, so I don't think it's an issue.
In the US, privacy means in your home. It cannot have a third party custodian.
* it's intuitive to use, so people who haven't seen it can quickly download what you send them without having to log in, being tracked and so on.
* password protection and expiry date for shared links come in handy
* superfast search is a boon for me as I have so many files it's probably the most important aspect
* the photos app in Next/ownCloud is underperforming if you have a large number of photos in a folder - the thumbnails seem to be generated each time I open the folder, it's probably a bug.
* when you need to collaborate, it's supereasy to add users and they intuitively know how to do things as they're used to Dropbox etc.