That said, I believe that Ruby and Python are both more robust languages on the whole. I suggest doing some generic (read: non-web) scripting in the languages and see what feels right, including community, documentation, and libraries.
Good read: http://www.codinghorror.com/blog/archives/001119.html
I think it really comes down to preference. I learnt PHP first off, then discovered the power of Ruby.
I suggest taking a look at this: http://www.killersites.com/blog/2006/php-vs-ruby/
So suppose I have an Idea and I'm searching to find out my co-founder who is a developer. shall I go for php developer or ruby? what are the elements which i should consider? and how this choice will effect me as the CEO in the future? for example is it hard to find a ruby developer or PHP? etc....
As for numbers, there are generally more PHP developers than Ruby developers, but you want a good developer, not just a developer.