The choice between Ruby and Python is something of a matter of taste. For what it's worth, Ruby on Rails appears to be more popular than Python's Django (though a quick search didn't give me any current numbers). In present day web development there is really no getting away from PHP, so you should learn it whether you choose Python or Ruby; same goes for JavaScript.

To make it easier to answer your question you should provide more background on your past programming and general computer experience.