I spend a lot of time in front of the computer, and I enjoy getting to know the tools that I find do their jobs well. Many of them are not free, but some of the most interesting ones that I use the most are available absolutely for free on the internet.
Photo Editing:
I enjoy using GIMP (the GNU Image Manipulation Program) for most of my photo editing needs. I find that it does essentially all that I need it to do, usually with little fuss or drama.
For Panorama Stitching, I use Hugin.
Office Software:
Although Google Docs is interesting and I enjoy using it, when I need a productivity software suite on a computer without Microsoft Office or an open and free office suite, I tend to gravitate towards OpenOffice.org or its offspring, LibreOffice.
PDF Creation:
I use PDFCreator for making PDFs. Although it does not do secure PDFs, it is fast, and just works for getting your documents in an easily published, predictable format.
Operating System:
Yes, I use Microsoft Windows. I also like Linux. My distribution of choice is Ubuntu (currently I use the Long-Term Support version 16.04.01), which you can download here. If you want to get it on a USB stick, you can use UNetBootin.
Web Browser:
A list of the software I use most would never be complete Google Chrome. After twenty-five years of Netscape, Mozilla, and Firefox, I have embraced Google's browser due to its speed, stability, and multi-platform integration. If you want to stay out of the Google universe, Chromium is the way to go.
Cell Phone:
I have a Google Pixel 3a XL. Pure Android is the best solution I have seen, and Google has done well keeping me happy with the Nexus and Pixel lines for many years. Nokia (HMD Global) also makes good phones, with pure Android and regular updates.