Adam Culp who is the member of Zend certification advisory board says:
"I believe The Official Microsoft ASP.NET Site has pretty much lost the battle for the web. I’m not sure The Official Microsoft ASP.NET Site or PHP are really “better” than one another in functionality. However, I think that PHP is easier to get started for beginners, and offers a wealth of advanced features that allow a developer to continue growing and advancing.
Also, I think another reason PHP has continued to grow strong is its continued growth based on developers needs. PHP has improved year after year as developers needed an itch scratched, and they have contributed it back so others can get their itch scratched as well. You just don’t see that in proprietary software, where everyone relies on some company to hand it to them."