I currently pay for Dropbox Professional at US$199 (or £147. I have a Dropbox account under the US$ billing system because it is a legacy account so I am not charged at the £199 price point). I pay for the Professional tier for the SmartSync really.
I try to minimalise paper from my life, so I scan every paper document I receive. I store formal documents such as birth certificates, and shred the rest. I have also started to backup most files I would use on my computer - super trusting the cloud with unimportant things - and using Boxcryptor file encryption within Dropbox, for the rest.
I also use it to transfer things between my work laptop and my personal computer (using Boxcryptor to encrypt sensitive documents). However because of GDPR, the IT guy at my school wants to disable Dropbox and only allow Tresorit due to end-to-end encryption and other things wrong with Dropbox in the past. The professional version of this is well over £200 so would significantly increase my cloud payments. I am currently trying it out though as my annuel Dropbox payment is due soon.
I also pay 79p per month for the lowest iCloud because I have all my historical and current photos in Apple Photos so need a bit of extra space.