Let's see an actual comparison with some numbers:
* Lines of code, and number of tasks necessary to get a development environment set up.
* Memory used with one client accessing the system, and with, say, 10 clients accessing it.
* Some performance benchmarks.
I keep my ear to the ground, and have used enough languages in my time that jumping to a new one isn't that big a deal, but I'm pretty happy with Rails and use it by default these days. It's a great way of getting something up and running quickly, while maintaining some order and sense of purpose to the code. It's what I'd use unless there are very clear reasons not to, such as huge scale requirements from the get-go, heavy involvement with web sockets or something like that where thinking a bit before coding is in order.