C# asp.net or Php for a web app?

I have an idea in mind for an application but i don't know what technologies to use. I want to make desktop app which would need to have a website and i would show different statistics from the desktop app in the website. So for i know only c++ so i can make the desktop part on C++ and learn Php. On the other hand i feel like i want learn C# .net WPF and asp.net(this is the thing i feel i would like learning more than Php). Can you please tell the pros and cons of this 2 languaeges ? I Would like to know which one is better for a big projects, consider that after learning one of this leanguages i will try find a job connected with this language. If i learn c# asp.net should i use MS SQL Server ?