I was impressed by how Madagascar integrates available open sources, such as python, (including numpy, scipy), VTK, LATEX, etc. More importantly, a GUI out of the box ready to be used by a new user significant reduces the learning curve. Users of Seismic Unix have to install third party software to access a GUI. Examples are Botoseis, GeBR. From this perspective, the winner is Madagascar. See the attached screenshot for a quick taste.