A report starts with a source table and conditions. Those choices determine what one row means before you choose a chart. An incident list contains incidents; Task SLAs contains attachments that can repeat the same parent task. A correct-looking bar chart on the wrong table can answer a different question.
Use a bar chart to compare groups, a pie chart for a small category breakdown, a list when users need record detail, and a single score for one aggregate. The chart type doesn't fix a flawed filter. Name the report so a manager can understand its scope without opening the definition. Inspect both the saved definition and the output when checking the result. A valid empty report should remain empty until matching source records exist.