I would ask myself "what in this project would rails fall short on? or what language has been known to do a better job, and don't think Ruby/Rails can do it?"

I would ask myself "what in this project would rails fall short on? or what language has been known to do a better job, and don't think Ruby/Rails can do it?" If there’s nothing compelling you to use something else, its up to you. but if you see something that Language Y could do over language X for this project, then that might be the indicator of which way to go. I do PHP work, currently I don’t feel I'm limited with the tools I've chosen for what I have in mind. If I did I'd certainly look to see where I've heard there is more opportunity. If you have the opportunity, pick the tools that would work for you and learn how to use them well.