I started with 1Password 4 (non-subscription) and considered upgrading to 1Password 7 -- yes, you could buy a non-subscription copy when I checked, although it's increasingly well hidden as an option -- and in addition to Dropbox it may have supported iCloud, not sure about that.
In the end I went with the subscription because I it's bought once for all my devices, and is great for family use, with UX that's easy from children to grandparents. As a bonus, the Dropbox sync issues just stopped - their own sync works much better for me.
I do understand the frustration about subscriptions for everything but I'd like my password manager vendor to remain in good financial health, so I'll happily make an exception and pay regularly for my password manager.
> just host the vaults on S3
That's a fairly niche audience, and it's very easy to misconfigure S3. Product development is about making hard choices, and I'm ok with 1Password choosing not to do this, just as I'm okay with them not supporting WebDAV -- YMMV.
What I do wish is that 1Password would support a few cloud storage options (e.g. Google Drive, OneDrive etc) on mobile so that people who're not inclined to subscribe have an alternative, if only to squelch the inevitable complaints about subscriptions. When 1Password was a smaller company, I can see why one wouldn't want to do that as it'd take away precious dev time, but my understanding is that they have more funding now.