I have yet needed to do a full restore, but I do partial restores from time to time to double-check my backup procedures and every time it's done what I wanted. My monthly costs are usually a bit under $5.

Note I essentially never use B2's API directly, and only use it as a backend through wrappers others have written, so I have no real experience with how good its API is. One of the few times I did try the API, I remember at one point I think I was getting Java exceptions back in the error messages, which was mildly concerning from a hygiene perspective and made for rather terrible error messages, but no sensitive data was being emitted. I also think that's been fixed.

The bottom line is that B2 has worked fine for me and at a good price point.

Did you mean to say 30 GB or 30 TB? Calling 30 TB as "smaller amount" seems weird to me in 2020, especially for personal data. Perhaps it would be the norm in a couple of decades. :)

FWIW, I have way under 1 TB of personal data to backup to different locations, and I consider that to be relatively large.