When you say "win", are you meaning in the sense of "there can only be one"?
Why limit the discussion to Python and Ruby? Why not include PHP, say? Why have Python and Ruby "lost" to PHP? What about C++, Java and C#?
Heck, VB is still more "popular" than either: http://www.tiobe.com/index.php/content/paperinfo/tpci/index....