Re: Dataverse and sharepoint list
Dataverse is a relational database that gives you the ability to preserve relationships among records. As well, a Dataverse table can handle something like 30 million rows, so you can work with relatively large data sets.
The biggest advantages over a SharePoint List are:
- More delegable operations for easier in-app queries
- Configurable Views for advanced filtering/sorting of data
- The capability to use FetchXML for advanced querying of data, particularly through relationships
From your other posts, I see you are still trying to get data out of an AS400 system, so that will be your primary hurdle. Dataverse offers additional ways beyond a CSV file to import data, which may help you out:

Hope that helps,
Bryan