I use LaTeX Beamer whenever I write a a presentation because
- I’m familiar with LaTeX and want to keep up with the skillset,
- I prefer to write in plain text, especially in emacs, and
- I don’t have to spend time working on the how the presentation looks and just have to worry about content.
I recently re-discovered S5, a way to make presentations using html, viewable by any web browser. I think it is safe to assume that more computers have a web browser than a pdf viewer (especially more than MS Powerpoint, for sure). I don’t really know html, so I searched for org-mode or markdown support. Of course, these exist. For org-mode, check out org-s5. For markdown support, there is Instiki and pandoc. I hope to try these out soon. S5 seems to be a good alternative when my presentation doesn’t involve math equations or source code on display. You can also create Beamer slides easily using org-mode; see this and this.