LaTeX Beamer and Prosper makes the most professionally typset documents with a large number of amazingly useful features not available from other types of presentation software.
License: Open Source
LaTeX Beamer is ideal for users needing high-quality, customizable presentations, especially in academia, but has a steep learning curve. Microsoft Office PowerPoint offers a user-friendly experience with strong collaboration tools but is less customizable than LaTeX. Prosper provides a middle ground but lacks some advanced features found in both LaTeX and PowerPoint.