The best export is the one your next tool can use without repair. Separate reading formats from subtitle formats and data formats before choosing an extension.
For reading and editing
TXT is easy to move between applications but carries no rich structure. Markdown adds headings and links in a portable text file. DOCX is useful when someone needs to rewrite, comment on or edit the document in a word processor.
For printing and sharing
PDF offers a stable reading layout. In Pyntic, select PDF and use Save as PDF in the browser print dialog. Check paper size, page breaks and preview before saving. A PDF is less convenient than the original text for extensive editing.
For subtitles
SRT and VTT need cue start and end times. Preserve measured times when importing captions. If you paste untimed text, exported timings are estimates; listen and align them before publishing a subtitle track.
For a data pipeline
JSON keeps segment fields explicit. CSV works well in spreadsheets; read its column headers before importing. HTML is useful for a simple readable page. Keep an untouched source export alongside transformed versions to make later corrections easier.