If you are fine with the command line, then nothing beats some combination of Ghostscript, ImageMagick, and PDFtk. OCR is much more complicated but I have used

If you are fine with the command line, then nothing beats some combination of Ghostscript, ImageMagick, and PDFtk. OCR is much more complicated but I have used Tesseract when OCR was needed. The results were mixed at best, sometimes being excellent and sometimes being terrible. It largely seems to be a function of the quality of the scan (how flat the text is, how horizontal the lines are, ...), though even seemingly minor deviations sometimes result in unreadable OCR text.