OneDrive or Sharepoint? for cloud storage and file server solution

Experts,

I have a client with a windows server standard FE (some kind of obsolete SBS) with around 230GB-300GB of work data they would like in the cloud, but my question is: is sharepoint or onedrive the way to go.

My Understanding of OneDrive is that it is personal and not quite suitable for a business integration. However I have not delved into the functionalities of Sharepoint. Azure is also an idea in terms of cloud server however I don't know if there needs to be some sort of LAN to LAN VPN connection to access it the same way they do their local file server.

But the client wants what the client wants, right? They want a live and constant sync to their PC's from whatever cloud file server solution they go for that is constantly accessible that looks and functions in the same basic way as the onsite file server. So for example if the internet goes down, they have the 9 o'clock sync to their PC's that they can work from, and when the internet comes back up and the connection to the cloud is re-established, the changes to the documents and work files syncs backup to the cloud.

So, would OneDrive/Sharepoint facilitate this and would it be advisable to use some kind of migration tool or can it be as easy as a copy and paste job over a weekend.

I look forward to reading all recommendations, thanks in advance.