The B2 “bring-your-own-client” version of Backblaze is popular with Duplicati users, per usage reports.
The Backblaze client’s disadvantages from my view include lack of good support for locked files, which Duplicati solves (if configured) with what it calls –snapshot-policy which on Windows is known as VSS.
Backing up photos probably won’t care, but other things (Microsoft Office files, perhaps, and maybe your email?) might need to occasionally be closed so the backup can get in. Does Backblaze support Volume Shadow Copy? discusses this. Another gripe is deleted files are only kept for 30 days. People who want careful manual control of what gets backed up might miss having it, but those wanting less configuration might favor it. People with lots of computers may balk at per-computer-pricing, and favor free clients and pay-by-size. I fall into the latter case, so am trying to help Duplicati progress towards being a great client. Such progress has been far slower than I’d like, but it’s basically limited by limited volunteers helping out.
Good plan. There are also reviews of their service (and others) around). Someone who’s highly IT-savvy might notice lack of geographic redundancy. If a disaster takes out a whole data center, it means trouble, however doing varied backups guards against that. There’s also no encryption of data in the data centers outside of what the client does, but both their client and Duplicati encrypt, which is arguably a better path.