[benologist]

The one more prone to success is the one that has a better person or team leading it to success, regardless of what it's built on. I can't even imagine a scenario where users actually care about the underlying stack, especially in any significant quantity.

With web apps the languages are all doing much the same thing anyway - they're taking data from a database and shoveling it on to pages. They're all going to suck and hurt at massive scale, they're all going to be worse at something than some other language, it's going to be hard to find awesome people for anything, and harder still to find awesome people who have previous experience solving the problems you face, most of which probably won't even be platform/technology related.