Ask HN: What alternatives to Powerpoint/Prezi are there?

I'm doing a lot of teaching and I've been using PowerPoint. I recently saw some people use Prezi and liked what they were able to do to map concepts visually to make them easier to understand. Unfortunately, it looks like a lot of the features that made Prezi powerful have been neutered in Prezi Next and isn't able to do a lot of what I'm looking for (no path editing, no infinite canvas, etc). What alternatives are there?

Some requirements for me:

* WYSIWIG editor * Tutorials * Infinite canvas/Path editing