The very popular LAMP setup is persistent in the community. Its open source, its widely available and after all, past Social Networks have done just fine using Linux, Apache, MySQL and PHP.<p>Why PHP? Why not something more <i>elegant</i> like Python or Ruby? My strength is PHP. Should I stop being choosy and just get hacking?
Lamp hasn't been lamp for a long time. Apache is interchangeable with lighttpd or nginx. Php can he replaced with perl, ruby, python or any other language you are productive in. Lamp describes a layered infrastructure design that is simple and scales well to a point. I don't imagine the language you choose will be a bottleneck in frontend web serving. Alot of it comes down to interaction wih your datastore. In that case it's largely down to how the data is structured.