Same here, Dropbox is the center of everything for me. I avoid Google Docs unless it's necessary to collaborate in real-time.
Apple Ads for the App Store have a super simple interface by default and it can be switched to an advanced one (which isn't complex either compared to something like Facebook Ads).
VLC for macOS…
Figma can't replace Illustrator when it comes to, well, illustration. I don't think that Illustrator is still used for UI design nowadays when there's Sketch-like Adobe XD for this.
The best…
Good threading UX. What Slack did is hard to follow and confusing because users need to decide if they reply in a thread or in place, and people tend to have different criteria for starting a thread…
Scapple: eight years later it still beats any other tool for thinking and collecting ideas over a long period. I have boards for different topics and projects that I revisit to "load" their overview…