TeamDrive are what we ended up using on my project when handling personal user data that we didn't want to share with the provider, after looking at the various offerings.
We considered SpiderOak as an alternative, but it didn't allow you to share a drive between multiple user accounts without losing the 'zero knowledge' property. (On SpiderOak, if you share a container between multiple accounts then SpiderOak can access the contents.) On TeamDrive, you can share between multiple accounts whilst still having zero knowledge.
We got an enterprise account for our project, but I'm pretty sure that the personal 10gb account is free.