To full-text index the PDF files in SharePoint 2007, most customers use the free PDF iFilter from Adobe. It's sort of the "default" option. There is a choice available though and it's always good to know the options :-)
Choices (in alphabetical order) available are:
Evaluating iFilter options
Extracting text and metadata from PDF documents is not a complex procedure and so accuracy of text extracted should not be a concern. There can be 2 parameters to evaluate the products:
Detailed Performance test results for the 3 products mentioned above are available on the Jie Li's GeekWorld blog. You can read the test details in - PDF iFilter Battle! FoxIT vs.. Adobe, 64bit version and PDF iFilter Battle, second round posts. Great work, Jie !
Conclusion is "On average, FoxIT x64 PDF ifilter is still ~5 times faster than the Adobe one" and "TET showed good performance, although still behind Foxit"
Since TET is licensed based on servers not cores, so it will get economical as number of Cores on the Server increases. Refer to the pricing comparison table created by Jie Li here
In my personal opinion, if performance is a concern/requirement than use the FoxIT iFilter otherwise install the free PDF iFilter from Adobe.