Couldabeen for presentations
When we had choice in the matter, you could buy
Aldus Persuasion (later bought by Adobe)
Then Adobe gave up on it, and decided that Acrobat would be the way to go, because they could do all this slideshow-type stuff in a PDF. However you would have to create your content in one of their other apps.
Current champ: Microsoft Powerpoint
Contender for second place: Apple Keynote