For me, Google video search, Google books (Internet Archive is good, but doesn’t always have the same stuff), Adobe InDesign (but in the process of learning LaTeX), and Typewise. As for the Google stuff, I liked Whoogle a lot, but almost all their instances seem to have been blocked or shut down. Also, apologies if this is repeating an earlier post.
Reaper DAW, and I have no plans on replacing because I like it. Also Reason, which I do have plans on replacing, but with what I haven’t a clue. Unfortunately, audio continues to lag way behind on Linux and open source. Additionally, VST is unfortunately THE standard for audio plugins, and they are indispensable in audio production.