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.
The problem with AWS is that one need to bring all storage from glacier to regular S3 (which is quite expensive), and then their egress costs are massive. I read more about it and completely agree that AWS is not worth it at all when pulling data in.
However, BackBlaze is quite expensive. I'd be paying $50 for my storage, which is simply not how much I'd like to pay. At this rate, I'd get a 10TB Ironwolf drive in an enclosure from Amazon for my cold storage.
TBH, I was looking at other providers, and Dropbox looks much less expensive at $20 for 9TB. It's a lot more than the 8TB I thought I'd be able to get away with for Glacier storage, but at least it's not $50. I will take a look at scaleaway, but I simply trust the bigger players to be around and keep my files safe than the smaller companies.
Edit: Scaleway seems less expensive than Dropbox with their glacier option. I really hope I can trust this company because this is an excellent price and I might even be willing to pay as much if it can be kept secure and safe. Now, I just need to read more about the value proposition of Dropbox vs Scaleway Glacier.
Regarding Dropbox: Where are you seeing 9 TB for 20 $? I'm in the EU so my pricing may vary, but all I can see is the Business plan for 16 € per month per user, with a minimum of 3 users in the plan, making it cost 48 € instead. Do you have access to something else?
Regarding Backblaze: Agreed that 50$ a month is a rough bill to pay, that sums up very fast if youre counting across the years. But their storage is also a lot more reliable than one single hard drive stored in a bank locker, with them always checking their arrays and replacing aged drives.
Regarding Scaleway: If im reading their pricing chart right, it would cost roughly 2 € / month / TB for glacier storage, and 9 € / TB when restoring from glacier to standard storage? A big questionmark for me is how ingress works. If I'm using this for backups in case of total system failure, i'll want to upload differential backups (borg/duplicati) every couple days. How is that going to work with pricing, is that all running through standard storage driving up monthly cost, do I have to manually manage file history and deletion of older stuff or does my backup software handle that? Plus, you loose out on the instant file access that you get with Backblaze, or with something hacky like Dropbox / Onedrive. I'm still undecided which I value more, money or fast access.
If I were to pay $50 a month for 8TB, I'd have paid about $200 in 4 months. I can get a 10TB-12TB external drive (with Ironwolf/WD Red Pro CMR inside) for about $200.