It is completely dependant on the recipient. While one customer might dismiss visuals and charts, others get too overwhelmed with raw data in an excel type format.

Best practice is to make the possibility of both available and let the user decide.

Ideally users can choose between self serve (dashboard style) and receiving reports by email (or both) and in the format (data or visual) they prefer.

Even with multiple users this can be easily tracked and managed with the right delivery tools.