Please explain: There are many web application framework available in the market especially some open source web frameworks.

12 important advantages ASP.NET offers over other Web development models:1. ASP.NET drastically reduces the amount of code required to build large applications.2. With built-in Windows authentication and per-application configuration, your applications are safe and secured.3. It provides better performance by taking advantage of early binding, just-in-time compilation, native optimization, and caching services right out of the box.4. The ASP.NET framework is complemented by a rich toolbox and designer in the Visual Studio integrated development environment. WYSIWYG editing, drag-and-drop server controls, and automatic deployment are just a few of the features this powerful tool provides.5. Provides simplicity as ASP.NET makes it easy to perform common tasks, from simple form submission and client authentication to deployment and site configuration.6. The source code and HTML are together therefore ASP.NET pages are easy to maintain and write. Also the source code is executed on the server. This provides a lot of power and flexibility to the web pages.7. All the processes are closely monitored and managed by the ASP.NET runtime, so that if process is dead, a new process can be created in its place, which helps keep your application constantly available to handle requests.8. It is purely server-side technology so, ASP.NET code executes on the server before it is sent to the browser.9. Being language-independent, it allows you to choose the language that best applies to your application or partition your application across many languages.10. ASP.NET makes for easy deployment. There is no need to register components because the configuration information is built-in.11. The Web server continuously monitors the pages, components and applications running on it. If it notices any memory leaks, infinite loops, other illegal activities, it immediately destroys those activities and restarts itself.12. Easily works with ADO.NET using data-binding and page formatting features. It is an application which runs faster and counters large volumes of users without having performance problems

My own opinion on this particular subject

Professional programmer is made of the difference between programming languages in general.

As for your question

Why do chose asp.Net for example when i can chose other alternatives that perform the same output

- The most important thing that I had the necessary licenses to use it.

- Compatibility with my web application server OS .

- The ease and speed of application development.

In the end there is no reason for me that I may chose between them if it was possible to design the same application and the same efficiency but that is personal convictions for programmer 

In My Opinion Make your Classes and Forget Third party Frameworks ...