Best way to set up data for future analysis - Pivots, Dashboards...

Greetings!

I have a pile of user-entered data (more about that some other time...) where users have entered multiple values in single cells.
These values are valid, but having multiple values in one cell makes things messy when one goes to analyze the data via pivot or create a dashboard.

What's the best way to set up this data, optimize for future analysis?

Should I separate out each value in a cell, creating an independent record for each value (repeating each line to separate out values) or leave the multiple values in each cell?

One produces a very didactic data spreadsheet, the other a lot of calisthenics to manipulate the data (separating string values, then concatenating, etc.).

Advice?

Many thanks!

J