In general, the idea of using QR codes is very good. Compared to plain text, they have pretty good error correction, so if the paper is partly damaged it will be still possible to decode them. They're also made specifically for scanning and reading into a computer via camera input, so you won't need to rely on the quality of an OCR software, even if those get better and better. Decoding QR via camera will be much more resilient and reliable.