Claude Sonnet is the strongest fit for parsing messy documents and converting them into structured table data. It excels at following precise extraction instructions, handling inconsistent formatting, and outputting clean CSV or markdown tables from unstructured text. You can paste or upload a document and prompt it to identify columns, normalize values, and fill gaps intelligently. ChatGPT is a solid alternative when you want a familiar chat interface with file upload support, and Claude Opus edges ahead for especially complex or ambiguous documents where deeper reasoning improves extraction accuracy.