The desktop client used to be just terrible. Has that changed? The Dropbox client does have its issues but it's really amazing at... Syncing files. I use it pretty creatively with large numbers of files and large volumes and it just works reliably.
I find Google Drive desktop to be just fine on Windows. Gave up a long time Dropbox sub for it and I have been happy. Dropbox just got too bloaty and unfocused for me.
This is more than S3 charges, but S3 will nickel and dime you aggressively for using that storage depending on your use case.
But $22/month buys an entire Google Workspace seat, which includes 5TB, for an effective $5.50/TB/month, which is quite a good deal. On the other hand, it’s rather lacking in flexibility.
I find this all somewhat confusing. At least one of these offerings does not reflect the underlying cost of the product.