Ask HN: What direction should i take for building my web app

I am trying to build a mobile web app whose content has top be crawled by search engines, its an idea that we are willing to test call it an MVP. Currently we are considering using AngularJS on the front-end and then Ruby for the webservice.

I have been thinking about how well angularJS apps work well with search engines as it is imperative that the site is crawlable and also what would be the most efficient language to build a fully functioning, scalable web service. We have the option of PHP, Ruby, Python.

Thanks in advance