The fastest transfer rates I could get were all with Dropbox (specially upload, as I have fiber at home and I expect a decent paying service to be prepared for customers). I decided to cancel my iCloud subscription because it was terribly slow for my godzillions of small files. I still pay for some Amazon Glacier storage too, for real long-term backups of memories and personal archives (haven't touched them in the last 5 years). If only Dropbox Smart Sync was cheaper I would pay for it so I don't have to sync all my stuff everywhere or selectively check out some folders only.