I'm a happy tarsnap user, but there are real reasons not to use it: the bus factor is 1, restores of large amounts of data are slowish, and data is stored at S3

I'm a happy tarsnap user, but there are real reasons not to use it: the bus factor is 1, restores of large amounts of data are slowish, and data is stored at S3-ish prices - which is to say, not cheap if you're storing terabytes of data. But tarsnap is indeed excellent.