Recently I looked into the same thing, since AWS caught my eye with their apparently ridiculously low prices. Then I found this (presumably indepdenant) review, that changed my view on things: https://b3n.org/b2-vs-s3-nas-backup/
After reading that, I won't go with AWS. I'm currently considering to abuse the OneDrive Office Family plan, which costs 99 $ a year for 6 TB of storage (split across 6 accounts), which comes down to 1,40 $ per month per TB. A price that I have not seen beaten by other storage / backup providers.