[NicoJuicy]

I've also known PHP, i'm mostly in Asp.Net MVC now (it's .Net)

But if you're starting from scratch and aren't using windows, i'd advice ruby on rails.

If you're using windows, choose between Rails 3.2 with Ruby 1.9.2 (bug with Ruby 2.0 on windows :( ) or Asp.Net MVC.

.Net will cost you something to, but just enroll as a startup (BizSpark) to get yourself going.

If you're going to Ruby On Rails, you should consider using Linux and Git all the time for deployment and compatibility though... But it works :-)