Ruby: +1 for Gem system and config management w/ bundler. +1 for DataMapper ORM and Active Record sucking less these days. -1 for everyone one thinking Ruby == Rails when it could be so much more. -1 for Ruby being less performant if you are not careful. +1 for nokogiri for slicing and dicing web pages.<p>Python: +1 for batteries included and tons of mature libraries and frameworks as well as some very mature async techology for the web. +1 for things that need to be fast have already been re-written as C extensions by now. -1 for dependency management and config stuff that is easier with Ruby and Clojure. +1 for Goggle App Engine no matter what the haters say.<p>PHP: +1 for everyone and their mother knows it. +1 for it fast runs on budget hosting. -1 for everyone and their mother thinks they are PHP rockstars and not everyone is. -1 for haters gonna hate startups that use it.<p>Java: Performant, stable, lots of mature frameworks. -1 supper verbose, not a lot of "fun" to write.<p>Clojure: +1 Lisp are pretty awesome. Easy to build up abstractions for the problem you are trying to solve. Frameworks tend to be manageable in size, dependecy management is at least as good as the Gem system for ruby. -1 not a lot of people know it. +/- 1 Love for Vim or Emacs required to be supper productive.<p>Erlang: +1 for the hard thinking about how to build something scalable and fault tolerant being done for you. -1 for the docs SUCK (still). You will need to buy many books and go to lots of meetups. -1 for the Erlang conference being so damn expensive that I can't afford a ticket. -1 for you probably having to drop in to C and write a Native Implementation Function (NIF) at some point. +1 that you can.<p>Nodejs: -1 for it's freaking Javascript. +1 for you are already going to be writing a tone of Javascript and context switching sucks. +1 for note package manager. +1 for having a BDFL in ryan.<p>Comedy option:
Cluster of mac minis running an Objective-C server (Hi Apple employees). Faster to develop web apps than C++ and very performant. -1 everything else.<p>But the real question is what stack are you most comfortable in. Shipping early and shipping often is more important than freaking anything! Pick whatever you are able to build a prototype in right this second.