为什么人们想要使用ruby而不是python，反之亦然？

I wanted to know, while deciding which language or technology to use for implementing an idea; a design, what are the factors involved in making a decision? Specifically talking about popular scripting languages, why would one choose to use ruby over python or perl or vice-versa? All these scripting languages have proved their worth, so how does one decide?I wanted to know, while deciding which language