A formatted spreadsheet, straight from History or Settings.
History → Export → Excel, or Settings → Data & export → XLSX. You get a formatted workbook that opens clean in Excel, Numbers, and Google Sheets. Free on every plan.
History page → Export menu → Excel for the filtered ledger you're looking at, or Settings → Data & export for the full account-wide dump. Same workbook format either way.
CSV is the universal raw format — great for tooling and imports. XLSX is formatted for humans: typed columns and clean sheets that open correctly without an import wizard. Same underlying data; pick per audience.