I just tried WinFindr and I am impressed with its speed and flexibility. I tested the file content search with docx and txt and it worked well. However, on PDF content search it missed much of what I searched for. The main PDFs I searched were invoices saved as PDFs from QuickBooks and downloaded bank statements. I know these are text PDFs because I can select and copy text from the PDF. Also, I built a rudimentary PDF content search program in Python with AI and it was able to find the right files using the same search string. I even took a txt file and printed using the Microsoft Print to PDF function and WinFindr was unable to search it. I am using version 1.6.
Other than this issue, WinFindr is a great search tool.