For my money, Ruby comes closest to realizing the &quot;promise&quot; of dynamic languages. That is, it&#x27;s fast to build with when prototyping, flexible when refactoring, reasonably fast enough and not so memory hungry that it can&#x27;t handle &quot;web scale&quot;.<p>Obviously there are languages that are better in each of these areas, but few that combine so many as well as Ruby. In other words, if you <i>know</i> that you&#x27;ll be working in a problem domain (e.g. high concurrency) where specific advantages of some other language (e.g. Go&#x2F;Erlang) are likely to be needed, use that language. If you&#x27;re just building <i>something</i>, then Ruby&#x27;s a fine place to start.