The best performing isn't markdown tables, it's markdown key/value pairs:

  ## Record 1
  
  ```
  id: 1
  name: Charlie A0
  age: 56
  city: New York
  department: Operations
  salary: 67896
  years_experience: 7
  project_count: 1
  ```

Which makes sense to me because the problem with formats like CSV and regular markdown tables is that it is too easy for the model to mistakenly associate a value in a row with the wrong header.

Explicit key/value formats like this or YAML or JSON objects make that a lot less likely.