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.
Clip Studio Paint IIt was way ahead than any commercial or FOSS alternative. Especially if you’re illustrator or comic artist working in specialized workflow (East Asia and SEA industry).
Tried Krita back then, but still lacks a lot of major important feature and customizable UI layout.