Powerpoint. I have contempt for Word, like Excel for editing tables (if it doesn't matter if it gets math right)

But with Powerpoint I can take "boxes and lines" diagrams right out of my head and onto the screen. It's also pretty good for making print graphics on odd-sized cards, say a 5x7 card that is used to make a "holder" for a punched card decoder, or a 8.5x14 poster about recyclable vs. not-recyclable plastics.

TeX -> PDF ... but I'm looking forward to trying this next time:

https://tools.suckless.org/sent/

Google Slides has come a long way since it launched. Has much of the feature parity with PowerPoint, better real-time collaboration and is free with a Gmail account.

I make a lot of slides. I went from PowerPoint to google slides and hated the transition, but then I went back to PowerPoint and I barely noticed. Google slides used to have some interoperability problems with other google docs (there were objects you can't copy/paste between slides, spreadsheets and docs). I don't know if those still exist. But otherwise, I don't see a huge difference anymore between google and PowerPoint. And if you have to use the web version (because you have linux e.g.) google might actually be a bit better.

emacs with org-mode and org-reveal. write a plain text file... get s presentation. use plant uml in the same text file and get a presentation with diagrams as fast as you can think.